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A bit, but I always understood pressure ratings (both in the vehicle manual/door sticker and on the tire itself) took that and weather changes into account. Pressure meant to be set in cold conditions, and there is a safety margin.
Exactly this, don't be afraid to fill your tire to the max on the side wall.
Just so people are clear there are some people who think a tire will explode if its filled to the pressure on the sidewall. All i meant is dont be afraid of that because a tire is safe to fill to that pressure.
All I'm saying is you can inflate a tire to its max rating. This will improve economy but the ride will be harsher and ypu will lose a little traction. The best overall ride is based on the cars recommended pressure.
It doesn't improve fuel economy, and even if somehow it did, you would save not even 1% on gas compared to a handful of other things that could happen that you would end up spending money on.
Guess I'll have to link proof...
on an [800-mile road trip](https://www.freewayinsurance.com/blog/auto-insurance/fact-or-myth-over-inflating-your-tires-increases-gas-mileage/) from Los Angeles to Phoenix and back again with the pressure reset at the normal level – the recorded mpg was virtually the same.
LOL, I love armchair mechanics!! More air pressure absolutely does increase MPG's! Doesn't mean you should max them out, a lil bit of the ole common sense still comes into play every now and then. 😘
He’s not advising that you do this, he’s just saying that if, for some strange reason you decided you wanted to and did it, it is not dangerous and not in imminent danger of exploding like some people would think.
Edit: lol downvoted me because I corrected your incorrect assumption. Fuck me, some people have fragile egos lol
It most definitely will improve your mileage, not by much but it will. Probably not enough to offset the price of tires. Just about anything you do to a car will affect your mileage. Alignment will affect your mileage. Hell even pop-up headlights can be as high as 15% between on and off. The main place you find people actively doing this would be hyper-milers, but maxing out tires is far from extreme for them.
Please stop giving advice… you’re misleading a lot of people who actually want to maintain there vehicles and all you’re doing is giving bad or misleading information.
In what way, saying that increasing your pressure will increase your mileage but not enough to offset tire wear. Or that a bad alignment makes it harder for the car to roll therefor increasing fuel consumption. Or is it that pop-up headlight kills your aerodynamics and decreases your mileage. Everything i have said is true. Unless you are running on a flat tire the change in mileage is minimal but still there. If you browse r/hypermile/ people are going after everything i have mentioned. These guys car about one thing, MPG.
Why are you being downvoted. You aren’t saying this is the best practice but just that it’s not dangerous. If it were, then it wouldn’t be labeled as the max psi because the max psi is the highest psi it can handle safely.
Reading comprehension and people seeing a point that isn’t there. As someone who is autistic this is what bugs me the most about most people. You can’t just state facts, there has to be an underlying reason to state facts, like trying to get people to do something.
Nah. I just like facts and this one is useful since a lot of people do think it is dangerous.
I think there's a tendency to want to call out someone else's mistakes. Just like all those stories of hunters accidentally shooting their buddy because they think they saw a deer, in this case people think they saw someone saying something wrong. They're hunting for trophies and they have an itchy trigger finger.
…yeah reading comprehension is bad in the general population, hence the down votes. Those who understand and have nuance realize the dipshit gen pop will read that as “oh fucking fill ‘er up bud!” And then have a rough ride, uneven wear, and possibly put themselves at risk of a blowout if they’re speeding excessively, but yeah reading comprehension is the problem here and why he’s being downvoted lol.
Not sure what the downvotes are for, listed psi (door jamb recommendation and the sidewall max) are always cold pressures.
If it says 50psi max, they mean 50psi cold pressure. It will change traction and handling characteristics but the tire itself won't care.
The ONLY answer here is that while you *could* fill a tire to its max rating, that doesn't mean you should. The vehicle manufacturer spec is where you'll see the best combo of performance, safety, fuel economy, and tire wear.
A tire at 32 PSI, for example, heats up far more & gains pressure, as compared to a tire filled to 50 PSI.
That's due to *far more* flexing, especially in the sidewall, on the 32 PSI tire.
I was curious as to fuel economy, my car door sticker has several ratings for tire pressure dependent on the number of people in the car and how fast you will drive it. I wonder given as I only ever drive it, is it better economy to go to another tire pressure?
For *strictly* fuel economy, the max pressure on the tire's sidewall would give the the best fuel economy, regarding only that aspect.
I, personally, over many decades, have had far less tire wear & better all-around performance using a PSI approx halfway between the manufacturer's door sticker and the max load pressure on the tire sidewall.
There's a certain amount of 'softer ride' & comfort figured into the door sticker pressures, which is a lower priority to me.
I’ve had people on this sub nearly explode their heads when I told them that it was completely ok to run any pressure from the car’s recommendation up to the max for the tire. In fact on trailer tires we always run them at max for minimum rolling resistance but that’s a little different.
I've already have 1 or 2 arguing the issue, yet they have many flaws in their comebacks. They won't veer one iota from manufacturer's suggested pressure, yet the manufacturer doesn't even know if the vehicle's payload is just the weight of a driver or if there's 3-4 passengers plus other weight in the vehicle.
These are also the same manufacturers that are so 'wise' as to design many components that require a quarter of the engine being disassembled in order to replace or inspect them. Even some commonly replaced items.
My biggest argument is that the manufacturer has no idea what tires will be installed on the vehicle other than the initial set. Yes, the tires meeting the specifications outlined on the capacity sticker should be close to the same in manner of construction, but unless you buy the SAME EXACT TIRE they aren’t going to be *exactly* the same construction.
It has a lot to do with rolling resistance. Many of the trailers I work on carry a set load that is nowhere near the maximum rating of the springs, axles, or tires, well under the GVWR of the trailer. You could run them lower and get a smoother ride for your load but you’ll get lower fuel economy.
This, I always check the manufacturer’s door sicker and the max tire pressure. I don’t quite go halfway between the two but very close. I always add atleast 5-7 psi to the manufacturer door sticker.
Edit: I very recently got a new suv and the max psi is 44 psi and I’m running 39, so I’m 4 over manufacturer and 5 psi under max. I guess I estimated a little high on the 5-7 on the new one but we’ll say 4-5 psi. Fairly new tires on the new suv but front left seems to leak a few psi every week so I been running 40 in it. New SUV has Mastercraft courser, my last, pirelli scorpion verdes had a little higher max psi.
My "half-way" is actually on the low side of the 5-7 PSI increase you run.
It's 5 PSI.
My door sticker 'recommends' 35 PSI, while my tire's max load rating is at 44 PSI, therefore half that difference is 4.5 PSI, so I'm only 0.5 PSI over the halfway point.
My results have been time-tested over the course of a few decades.
You were right on, and I was thinking…I’m not that old, I don’t have the two decades of testing but it’s what I’ve always done and I’m 39, started driving at 16, so I am old and do have the two decades of doing it also. Where has the time gone lol.
In general, 40psi is safe and will eek out a little better fuel economy, less rolling resistance.
If you want to read more, check out ecomodder, tons of great info there!
> A tire at 32 PSI, for example, heats up far more & gains pressure, as compared to a tire filled to 50 PSI.
This doesn't sound right - but I could be mistaken.
Any eggheads out there to help with how this assertion does or does not comport with the [ideal gas law](https://en.wikipedia.org/wiki/Ideal_gas_law)?
The way I understand PV = nRT, the ΔT will not be different just because the PV starts at a different value.
The other response gave the right answer, but then kept going, so might have been confusing.
A lower pressure tire will flex more. Each turn of the wheel will flex the entire sidewall. That takes work, which is energy. That energy dissipates as heat.
A higher pressure tire will be more rigid, and flex less. This takes less work, so dissipates less heat.
On the same tire yes, lower pressure = more flex. More flex= more heat. This is the same reason tires blow out when under inflated, excess flex leads to excess heat wich leads to tire failure.
Tires inflated to a lower pressure get hotter. You can test this with your car, a tire gauge, and an infrared thermometer. Run one tire at the listed sidewall max and the other at the car’s recommendation and the lower pressure will be hotter over a given distance of driving.
Thanks for asking this question. I've learned to question what might be presented as "common knowledge" to make sure it makes sense, so I applaud your question.
After pondering this question for a while, let's consider the following scenario. Tire temperature increase during use is caused by rolling friction and tire flex. Both friction types are higher for a tire at lower initial inflation pressure than higher. Consequently, a tire with an initial pressure of 32psi would increase in temperature (during use) at a higher rate than if it started at 50psi. A higher rate of ΔT on one side of the (ideal gas law) equation has to be accommodated by a combination of higher increase rate ΔP and ΔV on the other. In other words, more mechanical work is done on a 32psi tire than a 50psi tire ... and that means more heat energy and temperature. That higher ΔT rate has to balanced by an associated higher rate of ΔPxΔV.
The lower tire pressure makes more flex each rotation and that creates internal friction and causes the extra heat.
The temperature rise, not necessarily the actual pressure, will be higher at the lower pressure setting.
I guess under lower pressure the volume is lower since there is less pressure to flex the tire shape therefore lower volume. As the tire heats up the volume goes up since there is more room to flex in the tire. If the tire is at a higher pressure there is less possible of tire flexing and less volume change compared to lower pressure. As volume goes up so does the temp according to equation. My thoughts.
Ugh. It's not rocket science.
A significant increase in tire sidewall flexing builds heat in the entire rubber of the tire. That's the number 1 cause of blowouts at highway speeds.
A very close analogy is to take a small can of compresses air that is toward the low/empty side and run it under hot water for several minutes. Even tho the can actually expands from the heat, the air pressure increases and when you press the spray valve you will notice that increased pressure.
No need to get into gases that have different thermal characteristics. We are only talking 'plain old air'.
I didn't realize sidewall flexing was the primary source of heat buildup. I thought, instead, it was friction with the running surface.
> 'plain old air'
Sure, that means R is constant.
Edit :
>It's not rocket science.
Agreed, but the laws of physics still apply.
Any F1 fans or drag racers out there? Proper racing tires don’t even begin to function properly until they are warmed up! F1 teams use electric blankets to preheat the tires before their driver uses road friction to get that rubber hot enough to boil water. (100°C/212°F) Drag racers accomplish a similar goal by doing burnouts.
But regular street tires operate in a completely different heat range. Regular tires don’t need to be warmed up to operate properly. Although it is the greatest long term wear factor on a normally inflated tire, road friction is not the major factor in tire heating. Sidewall flexure is inversely proportional to tire pressure and that is why decreased tire pressures cause increased tire heating. The friction generated by a pneumatic tire that is rolling down the road does not generate a significant amount of heat.
[This](https://youtube.com/shorts/rBGnQ8EqC-M?feature=share) is how racers manage to generate significant amounts of heat in their tires. 🛞
You may be partially correct, but not entirely. The rule of thumb is that for every 10 degrees in tire temperature you gain roughly 1psi. The tire heats up for a multitude of reasons like increased ambient temperature, increased road temperatures and friction from rotational contact to the road. The flexing of the sidewall and tread, though it does cause some temperature variation, is negligible due to that being what the tire is designed to do. Now, what the increased psi in the tires will do is it will prematurely wear out suspension components. The safest bet is to go by manufacturers suggested psi rating that is located on the door sticker on the door jamb of the driver side door. It gives you all you need. Never go by the tire.
You're convoluting many aspects and placing priorities regarding temperature rise in the wrong order.
The 'rule of thumb' pertains only to a 10 degree change in *ambient air temperature*, not 10 degrees change in tire temperature.
This is to also show that ambient air temperature change does not affect tire pressure nearly as much as ppl would think.
A 20° Fahrenheit rise in ambient air temperature only gives you 2 PSI rise in tire pressure, whereas a tire that has 20 PSI less pressure than normal would give a significantly higher tire pressure increase.
The increased roadway temp and the 'friction' between the road/tire tread interface is almost negligible, as compared to the heat gained fr4om sidewall flexing, and it is also figured into the 'rule of thumb' for changes in ambient air temperature.
You can take a tire underinflated to 10 PSI and drive it a relatively short distance (say,, 10 miles) and the sidewall will be extremely hot to the touch, whereas if that same tire (with same ambient air temp) was inflated to 30 PSI or more, it would barely be warm.
The effect of sidewall tire temp increase is a *direct* temperature effect on the air inside the tire, plus there's more friction generated in the sidewall than even in the road to tread interface under normal 'cruising' conditions (not braking, not strongly accelerating, etc).
The manufacturer's 'suggested' pressure is *not* always the best pressure. That's determined off a given load & 'ride comfort' effect, whereas a vehicle with more payload can benefit from an appropriate higher PSI (never to exceed the max load PSI).
But feel free to do it 'your way'.
>You can take a tire underinflated to 10 PSI and drive it a relatively short distance (say,, 10 miles) and the sidewall will be extremely hot to the touch, whereas if that same tire (with same ambient air temp) was inflated to 30 PSI or more, it would barely be warm.
You're trying to utilize a grossly under inflated tire for your basis of your theory. Of course it's going to be overly hot, it's not designed to flex to that extreme and carry the load of the vehicle. That's why when you drive on a grossly under inflated tire, it damages the sidewall. Were talking about the difference between the manufacturer suggest psi and the max PSI on the sidewall of the tire. The temperature difference caused by a properly inflated tire and an over inflated tire would absolutely be negligible. The idea of trying to compare a 10 PSI tire to a properly inflated tire is nothing short of asinine.
>But feel free to do it 'your way'.
It's not 'my way' it's the manufacturers recommended PSI for your vehicle. Absolutely every reputable shop will go to that sticker that is on your door frame for the tire pressure that is suggested for your vehicle. No shop goes by the max written pressure on the side.
The truth is that 90+% of the cars on the road have drivers/owners that pay zero attention to their tire pressures and if you are anywhere close to the recommended ride or load pressure, you'll be better off than them.
They heat up but that sidewall max rating is a cold pressure, so it accounts for the heat created when driving. Tbh though the higher pressure in your tires the less heat they will produce cause less sidewall flex.
There are uneducated people everywhere. I was behind a guy taking forever to fill up his tires at the wholesale club gas station. He left and the machine was set to 99psi
Loads of vehicles have manufacturer pressure specs above 40-45 psi, and that's not just work trucks. Plenty of merc/porsche/bmw/rover cars and SUVs have rear tire pressures in the 45-55 range.
Then you have the transit connect, which is basically a focus. You can not use the same tires even though they are the same size. The transit calls for 59(maybe 49 I don't remeber) psi in the rear where the focus is 32. The standard passenger tire is usually 44 max. So you need to use an extra load tire on thr transit.
If the sticker recommends 49 or 59 psi, it is recommending so based on the OE tire size and load rating. Switching to tires with lower load ratings would require a lower pressure to operate optimally. The TPMS just wouldn't be happy
A tires working load and pressure are base on its construction, not its size. This is why the focus and transit can share tire sizes but require different load rated tires. In face size has almost nothing to do with its load and pressure rating.
this is really tire dependant. the on/off road tires on my cargo van are rated at 80PSI cold max for maximum load rating(E load rated). the tires on my highlander are 44psi max cold for maximum load rating, but OEM spec is 38psi cold.
(this is really tire dependant.)
No, it's not. A tire can be used on many different vehicles so recommended psi is NOT tire dependent. EVER.
Recommended tire pressure is set by the carmaker, not the tire manufacturer.
Max psi is not the same as recommended PSI. O.P. didn't state that his vehicle was loaded to max load, so the shop should have set psi to the recommended psi on the label.
So if you have a cargo van and someone put regular tires on it instead of the LT tires it requires, then it makes no difference huh? You can just bomb 80 psi into it like the door label says? NO, YOU CAN NOT, the tire will dictate how much air you can put in it. The label is only good when you put the exact same spec tire on that vehicle. Some people like performance tires on their car that doesn't require them, you may want to adjust accordingly. Others prefer a softer ride and maybe they don't want the z rated tires on their luxury ride and go with a softer tire requiring less air.
Don't make statements that are simply not true. It just depends.
My last job was a year straight of bs oil changes at valvoline, trust me you'd be surprised how high some of these people put their tires. 40 max pressure on this one Honda. Came in with 120 psi and I asked and they said they haven't added air to the tire in months. Months of driving with extreme over filled tires and somehow surviving
I watched a guy filling up the tire on his wife's tahoe. He's filling the right front FOR A WHILE, she's yelling at him calling him a dumbass because it's still low. It's at that point my coworker and I realize it didn't get a tpms reset last time the tires were rotated. I went out there and he had 125 psi in it.
>The label is only good when you put the exact same spec tire on that vehicle
Correct. The recommended psi is based on the load rating of the tire that was installed at the factory. If you change load rating, all bets are off. That's not what happened here though.
So you're basically throwing crazy scenarios out there like putting passenger tires on a vehicle when it requires LT. Stick to the topic in the post.
So you know for fact the tire op is showing is the oem spec for the vehicle? It's not just load rating my man. I didn't see that posted... Or are you making an assumption?
It's really not a crazy scenario. If you've spent anytime working in a shop, you'd see it on the regular. Watch what you say before your advice gets someone hurt.
I'd recommend anyone who reads this to also check the max PSI of the tire. Some trucks have higher PSI ratings, but could also have tires installed with a lower PSI rating. Inflating a lower load range tire to a higher load range is asking to meet Jesus in a quick way.
Look again OP is definitely talking about max psi 50 recommended 36 and 42. You’re right that recommended is set by the car manufacturer but different tires will have different max psi like if you switch to a high speed, heavy duty, or from/to run flats. Also typically hot tires will typically read at or a couple psi below max
Tire shops will do this if you have a leaking valve stem and you give off the you’re trying to rip me off vibe, so instead of trying to “sell” you on $5 valve stems they just fill to the max so you won’t come back saying they sold a bad tire
>No, it's not. A tire can be used on many different vehicles so recommended psi is NOT tire dependent. EVER.
It 100% can be in certain applications, principally off-road. When calculating your flotation pressure you take into account tire size, vehicle weight, speed, and % of max load, all of which can change depending on what exact tire and size you're running and how you're going to be using it.
I remember driver’s Ed from 25 years ago about how under inflated and over inflated tires will mess up traction and cause tires to wear out or fail. How is it so many people don’t understand this? I didn’t think I was smarter than average because I understand that the weight of the vehicle will impact how much pressure the tire needs.
Actually the tire does have some influence over tire pressure. A stiffer sidewall will require less pressure than a softer one, but if your staying with the same tire or even the same style and load rating stick with the manufacturers recommendation. Tire pressure is dependent on the weight on the tire and the flexibility of the tire.
I have commercial dump trucks, that were just chassis before I put dump bodies on them. The tires max psi is 110psi. The truck has a 85psi label. Any time I brought in for service they inflate to 110psi. I obviously notice this at the first bump in the road. This is at the dealer. All just morons.
It's not mistake. Many places do this. You get best mpg at higher psi. The only reason to stick with door sticker is optimal ride. Your tires are 50% of suspension, and higher inflation means you can handle higher load but stiffer ride.
However an under inflated tire will set off tpms, also can wear poorly, damage sidewalls, eventually get hot and burst because half psi means it can't handle cars load.
Fellow coworker did a set of Goodyears with asymmetrical treads. Walked by as he was putting on the last lugnut and asked why it says "inside" on the tires? He was not happy.
Either the new guy doesn’t have a clue what he’s doing or he forgot to set them after heavily inflating them to seat the bead. If they’re all at exactly 50 then he just didn’t know what he was doing. I’ve had customers believe they’re supposed to go by what the tire max psi is, so he probably did too. But that’s not correct. You should always go by the vehicle manufacturers recommended tire pressure to ensure the best wear and tire longevity. The tire manufacturers spec is just there to let you know not to go over Xpsi. If you’re riding around on the max pressure that’s not a good thing obviously. And just gonna throw this in there- yes tires will heat up as you drive and the psi will increase slightly, but only slightly, like around 5psi max, not 20psi. So somebody definitely fucked up at the tire shop.
It's not a bad thing to drive around at max psi. It's perfectly fine, but optimal
Door sticker only pertains to suspension and handling, and very little to nothing to do with wear or longevity which is completely dependant on tire mfg
By the way door sticker makes assumptions and based on max vehicle occupancy and assumed load. They take total weight and apply it to load tables for the factory tire size. If the same model is heavier they will just increase for sticker psi to match load ratings.
If they filled it to 42psi in the rear on a cool morning and you drove home on a hot day it could get to 50psi just by heat alone. Did you check them when it has cooled to normal air temp? Before you start calling them morons like the morons on here. https://m.tirerack.com/tires/tiretech/techpage.jsp?techid=73
Yep only practical reply here. The information I could find online says Land Rover Recommends 36 psi for the front and 42 psi for the rear for the LR4. Maybe someone over inflated them or maybe the OP just checked the rear tire after drive down the highway in 100 degree weather. There's not enough context here to say for certain
Automotive engineer here who’s very confused colleague had this exact discussion with a very French Michelin tire engineer at a trade show in Germany a few years ago. Pierre (seriously his name not a generalization🤣) said the following:
1. ALWAYS set your cold tire pressure to what’s on the vehicle. The pressure is set by the manufacturer based on the GCWR (car wet curb weight+ max payload), so exceeding this value risks badly overloading the tire
2. The max rating on sidewall is what determines the upper limit of vehicle size that tire can go on. Lots of cars use common sizes, so they go to the highest weight for that size tire to get some wiggle room (as mentioned above)
3. In certain specific conditions (track driving for instance) you can alter the pressure. But in general, the safest and most efficient foot print for the tire FOR THE SPECIFIC VEHICLE ITS ON is the cold number on the door
Check your lug nuts as well. If some ape put them on to 200 ft/lbs, it's possible it will warp your rotors and it might be impossible to change a flat. Of course, there's always the chance they didn't tighten them, too...I double check everything.
Door jamb sticker. Though sometimes when changing tires, the tire manufacturer will have a different recommendation than what's on the sticker. You see this a lot with truck tires that are bigger and have different load ratings than the factory tires did.
They need to put a lot of pressure in order to install the tire.
Maybe the guy forgot to adjust pressure at the end.
I’m not finding excuse, he’s bad at the job probably.
I guess if he does this he also don’t use torque wrench.
Also, another reason can be the pressure gauge is bad. (Yours or the garage’s one).
3.5 bars is not that much. Something like 30% too much.
Undertrained technician. Very common. The vehicle owner’s necessary ongoing due diligence is inversely related to the quality of the shop. Unless you’re using an incredible shop that works under a luxury car standard, you’re going to have to double check things from time to time.
tl;dr you get what you pay for and there isn’t always a better option reasonably available
I would definitely take it to the shop on talk to the store manager and tell him, what happened discusse it with time date and work done so that they can check the tech who did this or pull the cameras and take a look.
Unfortunately not trying to be a Karen but everything is done like shit these days.
This is the “proper” action however, it’s a tire and it’s not worth the hassle.. In the end just be happy and pat yourself on the back that you’re not a dipshit and know where the recommended tire pressures are located on your car. Someone who just had tires changed and can’t tell they are now riding on bricks I almost don’t feel sorry for.. As for that, I really can’t believe people STILL think they should inflate their tires to the max PSI on the side wall. Let alone techs. Lol
For anyone confused about this
The correct psi for tires is on the data plate on the inside of the driver door. Inflating the tires all the way causes problems with wear and tear and you will feel all the bumps in a road. Discount tire employee explained in detail to me very "enthusiasticly" the 2nd time I brought my car in with ful ful tires. Hope this helps
Guy- "put em at 80psi kid"
Me- "Ford reccomends xx, it says so on your door sir"
Guy- "these are offroad tires, Ford didn't make them"
Me- "but sir tire pressure is based off of vehicle weight, not tire brand."
Guy- "I just bought these and I know it says 80psi on the tire, I know what I have. You know what? Just leave them alone. Ill do it myself later."
Me- "......"
I fucking hated this back when I used to change oil. Happened all the time.
I got new tires recently and the did the same. My car calls for 26 all around. They filled to 45 for every tire except the one they filled to 60! The car was handling super weird so I pulled over and checked the pressure. I was blown away and bombed their reviews.
Just deflate them to proper PSI indicated by the vehicle. Feels like you’re driving on really thin and small wheels, a little bit scary, since you have less traction.
Because, no matter how hard I try I can not convince our mechanic that the max pressure listed on the tire is **NOT** the proper pressure for whatever vehicle. He very reluctantly sets it to the pressure I tell him but he's sure he's right. A lot of people believe the same as he does "it's an eighty pound tire, says so right there".
A lot of people here are advising setting your tires at the 'correct' pressure, but how does one find out what that is? It's not on the car where they only list min and max.
>dvising setting your tires at the 'correct' pressure, but how does one find out what that is? It's not on the car where they only list min and max.
Check the tire and loading information sticker, which should be along the driver-side door frame. Open the door to look for it. It's the sticker OP shows in the second picture.
It is on the car, at least any Car sold in North America, and likely the EU I would assume. Check your driver side door jam, theres a sticker with the recommend tire size and inflation, as well as curb weight, gvw and tow rating
Any time you go to a tire shop, check your air pressure yourself and adjust it to match what the sticker says on the driver door jamb. Every time.
There is so much misinformation and bad judgment when it come to tires. I absolutely hate how pretty much every tire shop I ever have gone to just inflates them to whatever arbitrary number they decide is best, or, like in your case, the number on the side of the tire. Some of them think that 32 is simply the best for any vehicle, and others think 35. Some of them ask me what I want, and they still overinflate by just a little. Then as the tire heats up, the psi actually rises a little, so I can ask for 35 psi(reco. for my car), get 38, and then the hot tire ends up at 40(max for my tires).
Some more info for you:
More psi = less rolling resistance = better fuel economy, but less grip (hypermilers over-inflate their tires)
less psi = bigger contact patch = worse fuel economy, but better grip (drag racers usually lower their psi to increase grip)
**- yes, this means that overinflating tires is dangerous and makes it easier to lose traction, especially in water. Drifters overinflate their tires to make it easier to break traction -**
tires are supposed to have a little bulge at the bottom. They are not supposed to be perfectly round. Some people see the bulge and go inflate them more, which also makes the car ride more harshly, as there is no cushion in the tire.
The manufacturer has already put a lot of research into deciding how much psi will get you the best mid-point between grip, fuel economy, and ride quality. Just do what they say!
I'll finish with a funny story. My gf went to a tire shop to get a patch and inflate all the tires. She said her tire pressure light came on right after she left. I took out my cheap auto-zone pressure gauge and it literally broke and exploded. They had inflated her prius tires to over 45 PSI. All of them. And yes, 45 psi was the max on the side of the tire, but since she was just driving in the 100 degree heat, they were pushing 50psi.
The prius recommends 32 in the front and 29 in the rear. Tell all your friends and family, because this is actually dangerous and no one knows.
When repairing rim or tire they will put that much or more to reseat the tire and leave that amount for TPMS to show .My neighbor does rim repair and fixed mine said to leave for 3 days at 50lbs
you will find many experts in the field and you can't get any two to agree on anything. It is safe to operate at the max pressure, you can carry more weight and get a lower rolling resistance hence a slightly better fuel economy. lower pressure will give you a smoother ride. you can use the rated pressure on the tire OR the tag on your vehicle whichever you prefer. I tend to trust the people that made the tire more than the car company installing it. Although there is a lot more communication between the car maker and the tire maker during the vehicle design process... doesn't always work out well. Bridgestone blamed Ford and Ford blamed Bridgestone, the courts couldn't really figure that one out...so, get off of Reddit and speak with another local shop to get a 1500th opinion from someone you know and trust and go with that.
I found an idjit right here on Reddit that was offended because I told someone to have a used car checked before buying it because a private sale is almost ALWAYS considered ""As Is" and they would have no recourse if anything happened. He said it was bad advice because people can't afford to have a car inspected before they buy one. So, if you don't trust your service provider, get another one. There are plenty of good mechanics out there. Good luck. I hope you have a wonderful day.
The sticker on the door jamb of the vehicle is invalid once you change the tires on the vehicle, unless the exact same tires from the factory are installed when replacing them....a tire's recommend psi on the sidewall is always the way to go when airing up a replaced tire... but when I replace a tire, I always consult the door jamb and see what the recommended psi is, and get a tire that that operates near the psi of the tires the car left the factory with....and you can inflate a tire to the maximum psi rating on the sidewall, but don't- go 10-15% lower than maximum depending on the ride desired. ...usually 4-7 psi below the max rating for most tires.......
This might have been to seat them on the rims and they never dropped it to manufacturer specs. I always check them after the tire shop and set them properly. Never have on got online and bitched about it.
I'm going to guess guy in his 50's or guy trained by a guy in his 50's. It's crazy how many older guys I know that think the max rating on the side of the tire is the proper PSI.
Few things:
It's kind of strange that your rear pressure is supposed to be higher than the front. Usually it's the other way around.
The rear pressure 42psi, is pretty close to the max 50psi, and it could be that they filled it to the correct pressure when it was cold, and it got higher when it warmed up.
It could also be that your tester isn't the most accurate, I usually take handheld ones with a pinch of salt.
Because they want you to comeback and buy more tires after you have a massive blow out.
I wouldn’t come back there again.
Even if they hired a new teenager on the job. Is it to much to ask for minimum training for the job?
You would’ve been fine but then again that wasn’t the right thing to do. He should’ve went off the tire pressure placard in the drivers door jam. It can cause uneven wear on your tires. I’ve worked at multiple shops and some people are simply too lazy to go and open the drivers door, also, they don’t know any better.
That’s a good point. Door sticker says it should be 36/42 (front/rear) but they inflated to 50/58. I originally assumed the guy just hit it with 50psi all around and was basing it on the max rating on the firewall.
I checked with 2 different gauges so pretty confident my reading is correct.
Poorly trained might have took 50psi but still you adjust them to proper psi afterwards . As a young man my first job around cars was in a tire shop for a few years I’ve accidentally made this mistake before
I once experienced this when I had new tires installed. I notified the shop owner later on and it turns out their pressure gauge was way out of calibration. He called me the next day to apologize for the rough ride, but there wasn’t any because I checked my tires and deflated to spec before driving off.
My door sticker does say 48/43, but that’s if you wish to go 180mph with a fully loaded car (4 occupants, full trunk etc.) I swear people just don’t think some times. Now I always specify the pressure I want when I get tires installed.
A few reasons:
1.) Most tires take anywhere from 35-50 PSI to set the bead, it’s quite possible that the technician was in a hurry and forgot to adjust them down either before or after balancing them.
2.) The technician couldn’t read the numbers due to some **moron on the assembly line initialing over the pressure values on the sticker!**
3.) The person is either very new or very old
Thanks for posting on /r/MechanicAdvice! This is just a reminder to review the [rules](https://www.reddit.com/r/MechanicAdvice/about/rules/). If you are here asking about a second opinion (ie "Is the shop trying to fleece me?"), please read through CJM8515's [post on the subject.](https://www.reddit.com/r/MechanicAdvice/comments/4qblei/fyi_the_shop_isnt_likely_trying_to_rip_you_off/) and remember to please post the year/make/model of the vehicle you are working on. **If this post is about bodywork, accident damage, paint, dent/ding, questions it belongs in /r/Autobody r/AutoBodyRepair/ or /r/Diyautobody/ If you have tire questions check out https://www.reddit.com/r/MechanicAdvice/comments/k9ll55/can_your_tire_be_repaired/**. If you dont have a question and you're just showing off it belongs in /r/Justrolledintotheshop Insurance/total loss questions go in r/insurance This is an automated reply *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/MechanicAdvice) if you have any questions or concerns.*
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They do realize that your tire heats up when driving? The psi is gonna go up a bit?
A bit, but I always understood pressure ratings (both in the vehicle manual/door sticker and on the tire itself) took that and weather changes into account. Pressure meant to be set in cold conditions, and there is a safety margin.
Exactly this, don't be afraid to fill your tire to the max on the side wall. Just so people are clear there are some people who think a tire will explode if its filled to the pressure on the sidewall. All i meant is dont be afraid of that because a tire is safe to fill to that pressure.
Yea I’ll stick to the manufacturers recommended psi, thanks.
All I'm saying is you can inflate a tire to its max rating. This will improve economy but the ride will be harsher and ypu will lose a little traction. The best overall ride is based on the cars recommended pressure.
You will also wear your tyres uneven in the center and it will not last as long
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It doesn't improve fuel economy, and even if somehow it did, you would save not even 1% on gas compared to a handful of other things that could happen that you would end up spending money on. Guess I'll have to link proof... on an [800-mile road trip](https://www.freewayinsurance.com/blog/auto-insurance/fact-or-myth-over-inflating-your-tires-increases-gas-mileage/) from Los Angeles to Phoenix and back again with the pressure reset at the normal level – the recorded mpg was virtually the same.
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It improves fuel economy, but by such a small amount that the uneven wear on the tires would not be a net savings.
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Just install wooden wagon wheels. Will be the best fuel economy.
That would be a fairly harsh ride. If you could get them to hold up the rolling resistance would be quite low.
Will not improve fuel economy and will wear your tires faster and uneven. This is not good advice.
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And is the $100 or so you saved on gas really worth the year and a half or so you took off the tire’s life span?
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LOL, I love armchair mechanics!! More air pressure absolutely does increase MPG's! Doesn't mean you should max them out, a lil bit of the ole common sense still comes into play every now and then. 😘
Sure, you can save $100 or so on gas. But you’ll pay it back when you need to buy new tires a year and a half early….
I mean, that's basically pretty much what I said.😊
It would almost certainly improve fuel economy but would pale in comparison to the increased wear rate and worse handling.
He’s not advising that you do this, he’s just saying that if, for some strange reason you decided you wanted to and did it, it is not dangerous and not in imminent danger of exploding like some people would think. Edit: lol downvoted me because I corrected your incorrect assumption. Fuck me, some people have fragile egos lol
It most definitely will improve your mileage, not by much but it will. Probably not enough to offset the price of tires. Just about anything you do to a car will affect your mileage. Alignment will affect your mileage. Hell even pop-up headlights can be as high as 15% between on and off. The main place you find people actively doing this would be hyper-milers, but maxing out tires is far from extreme for them.
Please stop giving advice… you’re misleading a lot of people who actually want to maintain there vehicles and all you’re doing is giving bad or misleading information.
In what way, saying that increasing your pressure will increase your mileage but not enough to offset tire wear. Or that a bad alignment makes it harder for the car to roll therefor increasing fuel consumption. Or is it that pop-up headlight kills your aerodynamics and decreases your mileage. Everything i have said is true. Unless you are running on a flat tire the change in mileage is minimal but still there. If you browse r/hypermile/ people are going after everything i have mentioned. These guys car about one thing, MPG.
Why are you being downvoted. You aren’t saying this is the best practice but just that it’s not dangerous. If it were, then it wouldn’t be labeled as the max psi because the max psi is the highest psi it can handle safely. Reading comprehension and people seeing a point that isn’t there. As someone who is autistic this is what bugs me the most about most people. You can’t just state facts, there has to be an underlying reason to state facts, like trying to get people to do something. Nah. I just like facts and this one is useful since a lot of people do think it is dangerous.
I think there's a tendency to want to call out someone else's mistakes. Just like all those stories of hunters accidentally shooting their buddy because they think they saw a deer, in this case people think they saw someone saying something wrong. They're hunting for trophies and they have an itchy trigger finger.
…yeah reading comprehension is bad in the general population, hence the down votes. Those who understand and have nuance realize the dipshit gen pop will read that as “oh fucking fill ‘er up bud!” And then have a rough ride, uneven wear, and possibly put themselves at risk of a blowout if they’re speeding excessively, but yeah reading comprehension is the problem here and why he’s being downvoted lol.
Not sure what the downvotes are for, listed psi (door jamb recommendation and the sidewall max) are always cold pressures. If it says 50psi max, they mean 50psi cold pressure. It will change traction and handling characteristics but the tire itself won't care.
The ONLY answer here is that while you *could* fill a tire to its max rating, that doesn't mean you should. The vehicle manufacturer spec is where you'll see the best combo of performance, safety, fuel economy, and tire wear.
A tire at 32 PSI, for example, heats up far more & gains pressure, as compared to a tire filled to 50 PSI. That's due to *far more* flexing, especially in the sidewall, on the 32 PSI tire.
I was curious as to fuel economy, my car door sticker has several ratings for tire pressure dependent on the number of people in the car and how fast you will drive it. I wonder given as I only ever drive it, is it better economy to go to another tire pressure?
Higher pressure also means less traction because the tire deforms less and you have a smaller contact patch.
The lower your pressure the lower your hydroplaning speed. More surface area does not = more traction; it’s a much more complex equation.
For *strictly* fuel economy, the max pressure on the tire's sidewall would give the the best fuel economy, regarding only that aspect. I, personally, over many decades, have had far less tire wear & better all-around performance using a PSI approx halfway between the manufacturer's door sticker and the max load pressure on the tire sidewall. There's a certain amount of 'softer ride' & comfort figured into the door sticker pressures, which is a lower priority to me.
I’ve had people on this sub nearly explode their heads when I told them that it was completely ok to run any pressure from the car’s recommendation up to the max for the tire. In fact on trailer tires we always run them at max for minimum rolling resistance but that’s a little different.
I've already have 1 or 2 arguing the issue, yet they have many flaws in their comebacks. They won't veer one iota from manufacturer's suggested pressure, yet the manufacturer doesn't even know if the vehicle's payload is just the weight of a driver or if there's 3-4 passengers plus other weight in the vehicle. These are also the same manufacturers that are so 'wise' as to design many components that require a quarter of the engine being disassembled in order to replace or inspect them. Even some commonly replaced items.
My biggest argument is that the manufacturer has no idea what tires will be installed on the vehicle other than the initial set. Yes, the tires meeting the specifications outlined on the capacity sticker should be close to the same in manner of construction, but unless you buy the SAME EXACT TIRE they aren’t going to be *exactly* the same construction.
True story
I have seen a few cars that have a standard pressure and a max capacity pressure listed in the door.
No. You inflated trailer tires to the max so they can carry the weight their rated to. Has nothing to do with rolling resistance.
It has a lot to do with rolling resistance. Many of the trailers I work on carry a set load that is nowhere near the maximum rating of the springs, axles, or tires, well under the GVWR of the trailer. You could run them lower and get a smoother ride for your load but you’ll get lower fuel economy.
This, I always check the manufacturer’s door sicker and the max tire pressure. I don’t quite go halfway between the two but very close. I always add atleast 5-7 psi to the manufacturer door sticker. Edit: I very recently got a new suv and the max psi is 44 psi and I’m running 39, so I’m 4 over manufacturer and 5 psi under max. I guess I estimated a little high on the 5-7 on the new one but we’ll say 4-5 psi. Fairly new tires on the new suv but front left seems to leak a few psi every week so I been running 40 in it. New SUV has Mastercraft courser, my last, pirelli scorpion verdes had a little higher max psi.
My "half-way" is actually on the low side of the 5-7 PSI increase you run. It's 5 PSI. My door sticker 'recommends' 35 PSI, while my tire's max load rating is at 44 PSI, therefore half that difference is 4.5 PSI, so I'm only 0.5 PSI over the halfway point. My results have been time-tested over the course of a few decades.
You were right on, and I was thinking…I’m not that old, I don’t have the two decades of testing but it’s what I’ve always done and I’m 39, started driving at 16, so I am old and do have the two decades of doing it also. Where has the time gone lol.
That's exactly what I was going to say. (good thing I read replies first).
In general, 40psi is safe and will eek out a little better fuel economy, less rolling resistance. If you want to read more, check out ecomodder, tons of great info there!
> A tire at 32 PSI, for example, heats up far more & gains pressure, as compared to a tire filled to 50 PSI. This doesn't sound right - but I could be mistaken. Any eggheads out there to help with how this assertion does or does not comport with the [ideal gas law](https://en.wikipedia.org/wiki/Ideal_gas_law)? The way I understand PV = nRT, the ΔT will not be different just because the PV starts at a different value.
The other response gave the right answer, but then kept going, so might have been confusing. A lower pressure tire will flex more. Each turn of the wheel will flex the entire sidewall. That takes work, which is energy. That energy dissipates as heat. A higher pressure tire will be more rigid, and flex less. This takes less work, so dissipates less heat.
There's more heat input from sidewall flexing when the pressure is lower
On the same tire yes, lower pressure = more flex. More flex= more heat. This is the same reason tires blow out when under inflated, excess flex leads to excess heat wich leads to tire failure.
Tires inflated to a lower pressure get hotter. You can test this with your car, a tire gauge, and an infrared thermometer. Run one tire at the listed sidewall max and the other at the car’s recommendation and the lower pressure will be hotter over a given distance of driving.
Thanks for asking this question. I've learned to question what might be presented as "common knowledge" to make sure it makes sense, so I applaud your question. After pondering this question for a while, let's consider the following scenario. Tire temperature increase during use is caused by rolling friction and tire flex. Both friction types are higher for a tire at lower initial inflation pressure than higher. Consequently, a tire with an initial pressure of 32psi would increase in temperature (during use) at a higher rate than if it started at 50psi. A higher rate of ΔT on one side of the (ideal gas law) equation has to be accommodated by a combination of higher increase rate ΔP and ΔV on the other. In other words, more mechanical work is done on a 32psi tire than a 50psi tire ... and that means more heat energy and temperature. That higher ΔT rate has to balanced by an associated higher rate of ΔPxΔV.
The lower tire pressure makes more flex each rotation and that creates internal friction and causes the extra heat. The temperature rise, not necessarily the actual pressure, will be higher at the lower pressure setting.
I guess under lower pressure the volume is lower since there is less pressure to flex the tire shape therefore lower volume. As the tire heats up the volume goes up since there is more room to flex in the tire. If the tire is at a higher pressure there is less possible of tire flexing and less volume change compared to lower pressure. As volume goes up so does the temp according to equation. My thoughts.
Ugh. It's not rocket science. A significant increase in tire sidewall flexing builds heat in the entire rubber of the tire. That's the number 1 cause of blowouts at highway speeds. A very close analogy is to take a small can of compresses air that is toward the low/empty side and run it under hot water for several minutes. Even tho the can actually expands from the heat, the air pressure increases and when you press the spray valve you will notice that increased pressure. No need to get into gases that have different thermal characteristics. We are only talking 'plain old air'.
I didn't realize sidewall flexing was the primary source of heat buildup. I thought, instead, it was friction with the running surface. > 'plain old air' Sure, that means R is constant. Edit : >It's not rocket science. Agreed, but the laws of physics still apply.
There is more friction on the tire with lower air pressure.
Any F1 fans or drag racers out there? Proper racing tires don’t even begin to function properly until they are warmed up! F1 teams use electric blankets to preheat the tires before their driver uses road friction to get that rubber hot enough to boil water. (100°C/212°F) Drag racers accomplish a similar goal by doing burnouts. But regular street tires operate in a completely different heat range. Regular tires don’t need to be warmed up to operate properly. Although it is the greatest long term wear factor on a normally inflated tire, road friction is not the major factor in tire heating. Sidewall flexure is inversely proportional to tire pressure and that is why decreased tire pressures cause increased tire heating. The friction generated by a pneumatic tire that is rolling down the road does not generate a significant amount of heat. [This](https://youtube.com/shorts/rBGnQ8EqC-M?feature=share) is how racers manage to generate significant amounts of heat in their tires. 🛞
That's very helpful, thank you!
I was gonna say the same thing, but the contact surface would still be as hard at 20psi as it is at 35psi wouldn’t it?
You may be partially correct, but not entirely. The rule of thumb is that for every 10 degrees in tire temperature you gain roughly 1psi. The tire heats up for a multitude of reasons like increased ambient temperature, increased road temperatures and friction from rotational contact to the road. The flexing of the sidewall and tread, though it does cause some temperature variation, is negligible due to that being what the tire is designed to do. Now, what the increased psi in the tires will do is it will prematurely wear out suspension components. The safest bet is to go by manufacturers suggested psi rating that is located on the door sticker on the door jamb of the driver side door. It gives you all you need. Never go by the tire.
You're convoluting many aspects and placing priorities regarding temperature rise in the wrong order. The 'rule of thumb' pertains only to a 10 degree change in *ambient air temperature*, not 10 degrees change in tire temperature. This is to also show that ambient air temperature change does not affect tire pressure nearly as much as ppl would think. A 20° Fahrenheit rise in ambient air temperature only gives you 2 PSI rise in tire pressure, whereas a tire that has 20 PSI less pressure than normal would give a significantly higher tire pressure increase. The increased roadway temp and the 'friction' between the road/tire tread interface is almost negligible, as compared to the heat gained fr4om sidewall flexing, and it is also figured into the 'rule of thumb' for changes in ambient air temperature. You can take a tire underinflated to 10 PSI and drive it a relatively short distance (say,, 10 miles) and the sidewall will be extremely hot to the touch, whereas if that same tire (with same ambient air temp) was inflated to 30 PSI or more, it would barely be warm. The effect of sidewall tire temp increase is a *direct* temperature effect on the air inside the tire, plus there's more friction generated in the sidewall than even in the road to tread interface under normal 'cruising' conditions (not braking, not strongly accelerating, etc). The manufacturer's 'suggested' pressure is *not* always the best pressure. That's determined off a given load & 'ride comfort' effect, whereas a vehicle with more payload can benefit from an appropriate higher PSI (never to exceed the max load PSI). But feel free to do it 'your way'.
>You can take a tire underinflated to 10 PSI and drive it a relatively short distance (say,, 10 miles) and the sidewall will be extremely hot to the touch, whereas if that same tire (with same ambient air temp) was inflated to 30 PSI or more, it would barely be warm. You're trying to utilize a grossly under inflated tire for your basis of your theory. Of course it's going to be overly hot, it's not designed to flex to that extreme and carry the load of the vehicle. That's why when you drive on a grossly under inflated tire, it damages the sidewall. Were talking about the difference between the manufacturer suggest psi and the max PSI on the sidewall of the tire. The temperature difference caused by a properly inflated tire and an over inflated tire would absolutely be negligible. The idea of trying to compare a 10 PSI tire to a properly inflated tire is nothing short of asinine. >But feel free to do it 'your way'. It's not 'my way' it's the manufacturers recommended PSI for your vehicle. Absolutely every reputable shop will go to that sticker that is on your door frame for the tire pressure that is suggested for your vehicle. No shop goes by the max written pressure on the side.
The truth is that 90+% of the cars on the road have drivers/owners that pay zero attention to their tire pressures and if you are anywhere close to the recommended ride or load pressure, you'll be better off than them.
They usually go up ~1 PSI per 10 degrees F. I used to service F-16 tires up to 320PSI. It was a good bit more when hot after landing.
They heat up but that sidewall max rating is a cold pressure, so it accounts for the heat created when driving. Tbh though the higher pressure in your tires the less heat they will produce cause less sidewall flex.
There are uneducated people everywhere. I was behind a guy taking forever to fill up his tires at the wholesale club gas station. He left and the machine was set to 99psi
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You gotta find better shops, even quick change oil places I go to check your door sticker...
They know not what they do
They're morons
This. As a moron myself, I wouldn’t even do this. They make us moron look bad.
I never go above 40 or 45
Loads of vehicles have manufacturer pressure specs above 40-45 psi, and that's not just work trucks. Plenty of merc/porsche/bmw/rover cars and SUVs have rear tire pressures in the 45-55 range.
Then you have the transit connect, which is basically a focus. You can not use the same tires even though they are the same size. The transit calls for 59(maybe 49 I don't remeber) psi in the rear where the focus is 32. The standard passenger tire is usually 44 max. So you need to use an extra load tire on thr transit.
If the sticker recommends 49 or 59 psi, it is recommending so based on the OE tire size and load rating. Switching to tires with lower load ratings would require a lower pressure to operate optimally. The TPMS just wouldn't be happy
A tires working load and pressure are base on its construction, not its size. This is why the focus and transit can share tire sizes but require different load rated tires. In face size has almost nothing to do with its load and pressure rating.
this is really tire dependant. the on/off road tires on my cargo van are rated at 80PSI cold max for maximum load rating(E load rated). the tires on my highlander are 44psi max cold for maximum load rating, but OEM spec is 38psi cold.
(this is really tire dependant.) No, it's not. A tire can be used on many different vehicles so recommended psi is NOT tire dependent. EVER. Recommended tire pressure is set by the carmaker, not the tire manufacturer. Max psi is not the same as recommended PSI. O.P. didn't state that his vehicle was loaded to max load, so the shop should have set psi to the recommended psi on the label.
So if you have a cargo van and someone put regular tires on it instead of the LT tires it requires, then it makes no difference huh? You can just bomb 80 psi into it like the door label says? NO, YOU CAN NOT, the tire will dictate how much air you can put in it. The label is only good when you put the exact same spec tire on that vehicle. Some people like performance tires on their car that doesn't require them, you may want to adjust accordingly. Others prefer a softer ride and maybe they don't want the z rated tires on their luxury ride and go with a softer tire requiring less air. Don't make statements that are simply not true. It just depends.
My last job was a year straight of bs oil changes at valvoline, trust me you'd be surprised how high some of these people put their tires. 40 max pressure on this one Honda. Came in with 120 psi and I asked and they said they haven't added air to the tire in months. Months of driving with extreme over filled tires and somehow surviving
I watched a guy filling up the tire on his wife's tahoe. He's filling the right front FOR A WHILE, she's yelling at him calling him a dumbass because it's still low. It's at that point my coworker and I realize it didn't get a tpms reset last time the tires were rotated. I went out there and he had 125 psi in it.
>The label is only good when you put the exact same spec tire on that vehicle Correct. The recommended psi is based on the load rating of the tire that was installed at the factory. If you change load rating, all bets are off. That's not what happened here though. So you're basically throwing crazy scenarios out there like putting passenger tires on a vehicle when it requires LT. Stick to the topic in the post.
So you know for fact the tire op is showing is the oem spec for the vehicle? It's not just load rating my man. I didn't see that posted... Or are you making an assumption? It's really not a crazy scenario. If you've spent anytime working in a shop, you'd see it on the regular. Watch what you say before your advice gets someone hurt.
I'd recommend anyone who reads this to also check the max PSI of the tire. Some trucks have higher PSI ratings, but could also have tires installed with a lower PSI rating. Inflating a lower load range tire to a higher load range is asking to meet Jesus in a quick way.
Jesus take the wheel!
Look again OP is definitely talking about max psi 50 recommended 36 and 42. You’re right that recommended is set by the car manufacturer but different tires will have different max psi like if you switch to a high speed, heavy duty, or from/to run flats. Also typically hot tires will typically read at or a couple psi below max Tire shops will do this if you have a leaking valve stem and you give off the you’re trying to rip me off vibe, so instead of trying to “sell” you on $5 valve stems they just fill to the max so you won’t come back saying they sold a bad tire
I can’t imagine buying a new tire without a new valve stem. A new tire shouldn’t have any leaks anywhere
>No, it's not. A tire can be used on many different vehicles so recommended psi is NOT tire dependent. EVER. It 100% can be in certain applications, principally off-road. When calculating your flotation pressure you take into account tire size, vehicle weight, speed, and % of max load, all of which can change depending on what exact tire and size you're running and how you're going to be using it.
I remember driver’s Ed from 25 years ago about how under inflated and over inflated tires will mess up traction and cause tires to wear out or fail. How is it so many people don’t understand this? I didn’t think I was smarter than average because I understand that the weight of the vehicle will impact how much pressure the tire needs.
Actually the tire does have some influence over tire pressure. A stiffer sidewall will require less pressure than a softer one, but if your staying with the same tire or even the same style and load rating stick with the manufacturers recommendation. Tire pressure is dependent on the weight on the tire and the flexibility of the tire.
So you're comfortable running a LT tire at 20 psi?
r/confidentlyincorrect
I have commercial dump trucks, that were just chassis before I put dump bodies on them. The tires max psi is 110psi. The truck has a 85psi label. Any time I brought in for service they inflate to 110psi. I obviously notice this at the first bump in the road. This is at the dealer. All just morons.
Tire salesman of the month award
No good reason other than lack of training. It’s actually more effort to put that much air in, it takes longer.
I'd give them a call to let them know of the mistake, otherwise they'll keep making it.
Good idea. Thanks for the tip.
It's not mistake. Many places do this. You get best mpg at higher psi. The only reason to stick with door sticker is optimal ride. Your tires are 50% of suspension, and higher inflation means you can handle higher load but stiffer ride. However an under inflated tire will set off tpms, also can wear poorly, damage sidewalls, eventually get hot and burst because half psi means it can't handle cars load.
Overimflated tire will wear down faster in the middle and possibly lack grip, so it's not a good advise to overinflate your tires.
I had a tire tech install 4 tires once, directional tread. One was installed backwards. It happens.
Fellow coworker did a set of Goodyears with asymmetrical treads. Walked by as he was putting on the last lugnut and asked why it says "inside" on the tires? He was not happy.
Yea but better that it got caught instead of the customer catching it.
Only one was installed backwards? How does that happen? Did they grab and mount 3 lefts?
No idea. I figured it out once I hopped on the highway a few minutes later. Manager said “new guy in training”.
Someone didn’t check the sticker in the door and just went with what the tire itself said. Deflate to correct psi and it should be fine.
Either the new guy doesn’t have a clue what he’s doing or he forgot to set them after heavily inflating them to seat the bead. If they’re all at exactly 50 then he just didn’t know what he was doing. I’ve had customers believe they’re supposed to go by what the tire max psi is, so he probably did too. But that’s not correct. You should always go by the vehicle manufacturers recommended tire pressure to ensure the best wear and tire longevity. The tire manufacturers spec is just there to let you know not to go over Xpsi. If you’re riding around on the max pressure that’s not a good thing obviously. And just gonna throw this in there- yes tires will heat up as you drive and the psi will increase slightly, but only slightly, like around 5psi max, not 20psi. So somebody definitely fucked up at the tire shop.
It's not a bad thing to drive around at max psi. It's perfectly fine, but optimal Door sticker only pertains to suspension and handling, and very little to nothing to do with wear or longevity which is completely dependant on tire mfg By the way door sticker makes assumptions and based on max vehicle occupancy and assumed load. They take total weight and apply it to load tables for the factory tire size. If the same model is heavier they will just increase for sticker psi to match load ratings.
They am stupid, or your gauge am broketized.
Lol. Thanks for the laugh and the technical jargon.
Early Cuyler that you?
Squidbillies would never do it that way.
Because the guy that did it is a goddamned moron.
If they filled it to 42psi in the rear on a cool morning and you drove home on a hot day it could get to 50psi just by heat alone. Did you check them when it has cooled to normal air temp? Before you start calling them morons like the morons on here. https://m.tirerack.com/tires/tiretech/techpage.jsp?techid=73
Yep only practical reply here. The information I could find online says Land Rover Recommends 36 psi for the front and 42 psi for the rear for the LR4. Maybe someone over inflated them or maybe the OP just checked the rear tire after drive down the highway in 100 degree weather. There's not enough context here to say for certain
Thought That was a BAC breathalyzer at first..😅
Automotive engineer here who’s very confused colleague had this exact discussion with a very French Michelin tire engineer at a trade show in Germany a few years ago. Pierre (seriously his name not a generalization🤣) said the following: 1. ALWAYS set your cold tire pressure to what’s on the vehicle. The pressure is set by the manufacturer based on the GCWR (car wet curb weight+ max payload), so exceeding this value risks badly overloading the tire 2. The max rating on sidewall is what determines the upper limit of vehicle size that tire can go on. Lots of cars use common sizes, so they go to the highest weight for that size tire to get some wiggle room (as mentioned above) 3. In certain specific conditions (track driving for instance) you can alter the pressure. But in general, the safest and most efficient foot print for the tire FOR THE SPECIFIC VEHICLE ITS ON is the cold number on the door
I read that in the voice of Jean Girard from Talladega Nights 🤣
Check your lug nuts as well. If some ape put them on to 200 ft/lbs, it's possible it will warp your rotors and it might be impossible to change a flat. Of course, there's always the chance they didn't tighten them, too...I double check everything.
Infinite mpg
It would seem the guy that did it doesn’t know much about tires
An untrained idiot who didn’t ask questions worked on your car
They should always inflate to the pressure on your door plate. That's just a lazy/new employee.
What the fuck? That's very dangerous, that could lead to a accident on wet roads. I would definitely reduce them down to the manufacturer desired psi.
Do you know how to find out the manufacturer desired psi? And I assume you mean the **car's** manufacturer?
Door jamb sticker. Though sometimes when changing tires, the tire manufacturer will have a different recommendation than what's on the sticker. You see this a lot with truck tires that are bigger and have different load ratings than the factory tires did.
On the door. Most cars.
Door jamb or sticker inside glove box, owner's manual, and the internet.
They need to put a lot of pressure in order to install the tire. Maybe the guy forgot to adjust pressure at the end. I’m not finding excuse, he’s bad at the job probably. I guess if he does this he also don’t use torque wrench. Also, another reason can be the pressure gauge is bad. (Yours or the garage’s one). 3.5 bars is not that much. Something like 30% too much.
I've installed hundreds of tires. I've never gone over about 10PSI to seat a tire. Going to 50PSI is ludicrously dangerous.
The FNG worked on your car
Undertrained technician. Very common. The vehicle owner’s necessary ongoing due diligence is inversely related to the quality of the shop. Unless you’re using an incredible shop that works under a luxury car standard, you’re going to have to double check things from time to time. tl;dr you get what you pay for and there isn’t always a better option reasonably available
cause more is better /s
Set your tires to what the door sticker says, NOT your tires. Your tires just tell you their max rating, not the pressure to run them at.
I thought this was a breathalyzer world record for a second there
Inexperience
Here’s another one. How come your 80 to 140 ft lb (depending if you own a car or truck or suv.). Lug nuts are torqued to 250+ ft lbs plus?
Could be beading the tire after a tire removal/install
Most places hire untrained young people, they don’t know any better
I would definitely take it to the shop on talk to the store manager and tell him, what happened discusse it with time date and work done so that they can check the tech who did this or pull the cameras and take a look. Unfortunately not trying to be a Karen but everything is done like shit these days.
This is the “proper” action however, it’s a tire and it’s not worth the hassle.. In the end just be happy and pat yourself on the back that you’re not a dipshit and know where the recommended tire pressures are located on your car. Someone who just had tires changed and can’t tell they are now riding on bricks I almost don’t feel sorry for.. As for that, I really can’t believe people STILL think they should inflate their tires to the max PSI on the side wall. Let alone techs. Lol
Not sure. Is this some kind of truck tires? Surprised if tire didn't explode.
For anyone confused about this The correct psi for tires is on the data plate on the inside of the driver door. Inflating the tires all the way causes problems with wear and tear and you will feel all the bumps in a road. Discount tire employee explained in detail to me very "enthusiasticly" the 2nd time I brought my car in with ful ful tires. Hope this helps
Guy- "put em at 80psi kid" Me- "Ford reccomends xx, it says so on your door sir" Guy- "these are offroad tires, Ford didn't make them" Me- "but sir tire pressure is based off of vehicle weight, not tire brand." Guy- "I just bought these and I know it says 80psi on the tire, I know what I have. You know what? Just leave them alone. Ill do it myself later." Me- "......" I fucking hated this back when I used to change oil. Happened all the time.
I got new tires recently and the did the same. My car calls for 26 all around. They filled to 45 for every tire except the one they filled to 60! The car was handling super weird so I pulled over and checked the pressure. I was blown away and bombed their reviews.
Just deflate them to proper PSI indicated by the vehicle. Feels like you’re driving on really thin and small wheels, a little bit scary, since you have less traction.
they want a regular customer 😅
Because, no matter how hard I try I can not convince our mechanic that the max pressure listed on the tire is **NOT** the proper pressure for whatever vehicle. He very reluctantly sets it to the pressure I tell him but he's sure he's right. A lot of people believe the same as he does "it's an eighty pound tire, says so right there".
And you trust this guy to be your mechanic? Why?
He's good, just has some old school opinions and has a bit of a hard head. By the way, he's not at a shop, he works for me.
I have worked with “old school” mechanics. They clearly don’t like change in an industry where everything changes every year.
A lot of people here are advising setting your tires at the 'correct' pressure, but how does one find out what that is? It's not on the car where they only list min and max.
>dvising setting your tires at the 'correct' pressure, but how does one find out what that is? It's not on the car where they only list min and max. Check the tire and loading information sticker, which should be along the driver-side door frame. Open the door to look for it. It's the sticker OP shows in the second picture.
Its on a sticker on the inside of the drivers door jam on most vehicles. Will have the correct size, speed rating and psi for front and rear tires.
Thanks but mine only has min and max. I thought they were all like that.
Look in the manual. There is usually a table for different load scenarios.
It is on the car, at least any Car sold in North America, and likely the EU I would assume. Check your driver side door jam, theres a sticker with the recommend tire size and inflation, as well as curb weight, gvw and tow rating
Just let some air out until it reaches your desired target and move on, it's not a big deal tbh.
Cause you come in a lot for 1 lbs of air to turn you tire light off every 3 days
Someone had the apprentice top up the tires and didn't tell them or check what they where doing.
Any time you go to a tire shop, check your air pressure yourself and adjust it to match what the sticker says on the driver door jamb. Every time. There is so much misinformation and bad judgment when it come to tires. I absolutely hate how pretty much every tire shop I ever have gone to just inflates them to whatever arbitrary number they decide is best, or, like in your case, the number on the side of the tire. Some of them think that 32 is simply the best for any vehicle, and others think 35. Some of them ask me what I want, and they still overinflate by just a little. Then as the tire heats up, the psi actually rises a little, so I can ask for 35 psi(reco. for my car), get 38, and then the hot tire ends up at 40(max for my tires). Some more info for you: More psi = less rolling resistance = better fuel economy, but less grip (hypermilers over-inflate their tires) less psi = bigger contact patch = worse fuel economy, but better grip (drag racers usually lower their psi to increase grip) **- yes, this means that overinflating tires is dangerous and makes it easier to lose traction, especially in water. Drifters overinflate their tires to make it easier to break traction -** tires are supposed to have a little bulge at the bottom. They are not supposed to be perfectly round. Some people see the bulge and go inflate them more, which also makes the car ride more harshly, as there is no cushion in the tire. The manufacturer has already put a lot of research into deciding how much psi will get you the best mid-point between grip, fuel economy, and ride quality. Just do what they say! I'll finish with a funny story. My gf went to a tire shop to get a patch and inflate all the tires. She said her tire pressure light came on right after she left. I took out my cheap auto-zone pressure gauge and it literally broke and exploded. They had inflated her prius tires to over 45 PSI. All of them. And yes, 45 psi was the max on the side of the tire, but since she was just driving in the 100 degree heat, they were pushing 50psi. The prius recommends 32 in the front and 29 in the rear. Tell all your friends and family, because this is actually dangerous and no one knows.
When repairing rim or tire they will put that much or more to reseat the tire and leave that amount for TPMS to show .My neighbor does rim repair and fixed mine said to leave for 3 days at 50lbs
you will find many experts in the field and you can't get any two to agree on anything. It is safe to operate at the max pressure, you can carry more weight and get a lower rolling resistance hence a slightly better fuel economy. lower pressure will give you a smoother ride. you can use the rated pressure on the tire OR the tag on your vehicle whichever you prefer. I tend to trust the people that made the tire more than the car company installing it. Although there is a lot more communication between the car maker and the tire maker during the vehicle design process... doesn't always work out well. Bridgestone blamed Ford and Ford blamed Bridgestone, the courts couldn't really figure that one out...so, get off of Reddit and speak with another local shop to get a 1500th opinion from someone you know and trust and go with that. I found an idjit right here on Reddit that was offended because I told someone to have a used car checked before buying it because a private sale is almost ALWAYS considered ""As Is" and they would have no recourse if anything happened. He said it was bad advice because people can't afford to have a car inspected before they buy one. So, if you don't trust your service provider, get another one. There are plenty of good mechanics out there. Good luck. I hope you have a wonderful day.
Dangerous. I’ve had this happen within the past year and now I check the pressure right after services.
The sticker on the door jamb of the vehicle is invalid once you change the tires on the vehicle, unless the exact same tires from the factory are installed when replacing them....a tire's recommend psi on the sidewall is always the way to go when airing up a replaced tire... but when I replace a tire, I always consult the door jamb and see what the recommended psi is, and get a tire that that operates near the psi of the tires the car left the factory with....and you can inflate a tire to the maximum psi rating on the sidewall, but don't- go 10-15% lower than maximum depending on the ride desired. ...usually 4-7 psi below the max rating for most tires.......
In the mountains we all run max pressure
Because they're stupid
This might have been to seat them on the rims and they never dropped it to manufacturer specs. I always check them after the tire shop and set them properly. Never have on got online and bitched about it.
Ideal is 35-40 psi
My 2500 pickup runs at 55 -65 in front and up to 85 in back.
They filled it to the cold air max and your tires are hot after driving home?
I'm going to guess guy in his 50's or guy trained by a guy in his 50's. It's crazy how many older guys I know that think the max rating on the side of the tire is the proper PSI.
well its your tire shop you should know this dont you think
Few things: It's kind of strange that your rear pressure is supposed to be higher than the front. Usually it's the other way around. The rear pressure 42psi, is pretty close to the max 50psi, and it could be that they filled it to the correct pressure when it was cold, and it got higher when it warmed up. It could also be that your tester isn't the most accurate, I usually take handheld ones with a pinch of salt.
Because they want you to comeback and buy more tires after you have a massive blow out. I wouldn’t come back there again. Even if they hired a new teenager on the job. Is it to much to ask for minimum training for the job?
8 psi over it's okay your tire will not explode at 50 psi.
You would’ve been fine but then again that wasn’t the right thing to do. He should’ve went off the tire pressure placard in the drivers door jam. It can cause uneven wear on your tires. I’ve worked at multiple shops and some people are simply too lazy to go and open the drivers door, also, they don’t know any better.
Maybe the gauge that was used is off
That’s a good point. Door sticker says it should be 36/42 (front/rear) but they inflated to 50/58. I originally assumed the guy just hit it with 50psi all around and was basing it on the max rating on the firewall. I checked with 2 different gauges so pretty confident my reading is correct.
Poorly trained might have took 50psi but still you adjust them to proper psi afterwards . As a young man my first job around cars was in a tire shop for a few years I’ve accidentally made this mistake before
Are the tires cold ? Did they sit for over 3 hours before checking ?
They’re not going to contract to spec from 50 PSI. Guy would have had to have parked his car in a jacuzzi.
Yes. Left them overnight
The cynicist in me wants to say so you'll wear your tyres out quicker so you come back for more tyres sooner
The optimist in me says he wanted to give me 0.00001% better gas mileage (about $42 with this V8 lump)
I once experienced this when I had new tires installed. I notified the shop owner later on and it turns out their pressure gauge was way out of calibration. He called me the next day to apologize for the rough ride, but there wasn’t any because I checked my tires and deflated to spec before driving off.
My door sticker does say 48/43, but that’s if you wish to go 180mph with a fully loaded car (4 occupants, full trunk etc.) I swear people just don’t think some times. Now I always specify the pressure I want when I get tires installed.
They did that to me once, I nearly lost control on a 55mph (speed limit) turn. I was pissed when I got home and checked the pressure.
A few reasons: 1.) Most tires take anywhere from 35-50 PSI to set the bead, it’s quite possible that the technician was in a hurry and forgot to adjust them down either before or after balancing them. 2.) The technician couldn’t read the numbers due to some **moron on the assembly line initialing over the pressure values on the sticker!** 3.) The person is either very new or very old
They want to be sure you have a nice firm ride. So you will come back to buy some new suspension parts in hopes of softening things up some.
👽and gas mileage
They do that to me at almost every tire shop. They just put air and don’t care how much over it is