What is the correct pressure for inflating tires? inside door label or side of tire?

[nonlinear]

What pressure do you guys inflate your tires to? my dad has some auto repair shops, and as a kid or when I used to work for him in high school, he taught me to inflate tires to the maximum pressure given on the side of the tire. However, i've read in many places (e.g. http://www.fueleconomy.gov/feg/maintain.shtml) that tires should be inflated to the pressure suggested by the vehicle manufacturer, which is given on the label on the side of the driver's door.

just curious, since i had my car in for an oil change today, and the guy let out the air from 44 psi to 32 psi (although i'm not sure if my door says 32, or if the guy didn't read the tire and just assumed it was 32 psi).

what do you guys do?

[revelations]

Chassis sticker - tuned by OEM to make car handle as intended.


If I changed tires and/or rims that signifigantly deviated from OEM, I would run something other than max sidewall PSI or chassis sticker.

[ercchry]

i thought you were an educated man? tell me... WHY THE HELL you would inflated to the MAXIMUM pressure when the tires are cold!?????!!!! :facepalm:

[Twin_Cam_Turbo]

I never ever inflate to maximum pressure unless im seating the beads. OEM reccomended pressure always unless its significantly different from stock.

[Sugarphreak]

.....

[rizfarmer]

I just had my car in to repair a flat and the shop inflated all of my tires to 40psi on a 2 door integra in the cold of winter. That's about 90% of max pressure and way up from the manufacturers recommendation. WTF?

btw I dropped it back to about 32 psi, which is still a little above the Acura recommendation

[nonlinear]

so I just looked at the sticker on my car door, and it says 30 psi for all the tires. the sidewalls say 44 psi max.

then i took a look in the owner's manual for my car, and it says this:

"A Tire and Loading information label is attached to the vehicle's center pillar, below the driver's door latch. This label lists your vehicle's original equipment tires and their recommended cold tire inflation pressures. The recommended cold tire inflation pressure, shown on the label, is the minimum amount of air pressure needed to support your vehicle's maximum load carrying capacity."

it doesn't say anything about what pressure to inflate if non-OEM tires are installed. But I would imagine that if I inflate my 44psi tires at 30 psi, it's going to cause excessive flex, heat, etc. and will reduce the life of my tires. :confused:

[ercchry]

Originally posted by nonlinear
s

it doesn't say anything about what pressure to inflate if non-OEM tires are installed. But I would imagine that if I inflate my 44psi tires at 30 psi, it's going to cause excessive flex, heat, etc. and will reduce the life of my tires. :confused:

...no

think of it like this.... a ballon can hold 44psi before exploding.... do you fill it to 30psi... or do you fill it right to the max of 44psi?

[nonlinear]

^^dude, the max inflation pressure if FAR from the blowout pressure. and you don't want inderinflated tires, either. this is from my manual:

NOTICE: Do not let anyone tell you that under-inflation or over-inflation is all right. it is not. if your tires fo not have enough air (under-inflation), you can get the following:

-too much flexing
-toomuch heat
-tire overloading
-premature or irregular wear
-poor handling
-reduced fuel economy

too much air:
-unusual wear
poor handling
-rough ride
-needless damage from road hazards.

since the car manufacturers recommendation is the "minimum PSI required to support the maximum load capacity," i conclude that I should run my tires near the maximum recommended by the tire manufacturer, as long as tire value > car value. i've been reading inflation arguments on other forums, too, and conclude this from reading there also.

[ercchry]

have you noticed what happens when you add heat to a tire? (think drag car doing a burn out)

tell me, if you set your pressure to the maximum when the tire is cold, will if not be over that maximum when heated?

EDIT: and minimum pressure for MAXIMUM load? do you often carry around that sort of weight?

[nonlinear]

Originally posted by ercchry
have you noticed what happens when you add heat to a tire? (think drag car doing a burn out)

tell me, if you set your pressure to the maximum when the tire is cold, will if not be over that maximum when heated?


yes, i understand what you are getting at (ideal gas law hehe) ;) however, the max inflation given on the sidewall is a cold inflation value... i.e. the changes in gas volume with temperature are already accounted for.

and, if temp really is a concern, you should keep your tires near max inflation, since under-inflated tires get hotter than properly-inflated tires. actually, i had a leak in a tire on one of my old cars, and when i pulled in to a gas station the tire was so hot it was steaming (from snow)... the plys eventually separated from that tire, and i'm guessing it was due to damage from the excess heat.


Originally posted by ercchry

EDIT: and minimum pressure for MAXIMUM load? do you often carry around that sort of weight?

no i don't, but note that it's MINIMUM pressure. the car manufacturer doesn't say anything about maximum pressure... that depends on the tire design, which is why the tire manufacturer gives the max pressure.

[GTS4tw]

Originally posted by ercchry


...no

think of it like this.... a ballon can hold 44psi before exploding.... do you fill it to 30psi... or do you fill it right to the max of 44psi?

I don't usually agree with nonlinear, but wtf are you smoking? I fill to 5psi under on 44psi tires because I have found it to be optimal for fuel mileage and comfort, but I would be fully comfortable at max pressure. The tires will not blow up at 44psi (or 54 or 64.... but I digress) they will be quite hard and will lose grip on slippery surfaces, but there is no danger.

Also, on your other "fact" the max pressure is tested at COLD.

[ercchry]

yes.. there is minimums and there is maximums, why would you run either? you need a balance, if you do not you will get uneven tire wear... like so:

http://www.mpi.mb.ca/Images/60SecondDriver/tireinflation.jpg

[nonlinear]

^^yes, however "proper inflation" in that diagram is the maximum inflation pressure given on the sidewall of the tire.

[ercchry]

Originally posted by nonlinear
^^yes, however "proper inflation" in that diagram is the maximum inflation pressure given on the sidewall of the tire.

i doubt it, you know why? i have ran many, many different tires, sizes, diameters, and brands... i have got the over inflated results at less then the maximum sidewall psi.... you would be amazed at how the traction levels drop on a regular passenger car tire around the 40psi mark

[89s1]

Much like the picture in his signature nonlinear must see everything as black & white.

I honestly don't see whats so hard to understand, but he has a hard time with lots of things that seem pretty logical to me... :dunno:

[nonlinear]

oops

[nonlinear]

Originally posted by ercchry


i doubt it, you know why? i have ran many, many different tires, sizes, diameters, and brands... i have got the over inflated results at less then the maximum sidewall psi.... you would be amazed at how the traction levels drop on a regular passenger car tire around the 40psi mark

yea i've never worn through a set of tires enough to see the long-term wear patterns. but i've always ran at maximum recommended inflation. :dunno:

i have yet to see a convincing argument of why to run below max inflation. i've also read quite a bit about why under-inflation is bad. :dunno:

[89s1]

Inflating to maximum pressure leaves less room for expansion of the air as it comes up to temperature. Get it? Set it to max cold, it quickly goes above max when driving long distances or on a nice hot day.

[nonlinear]

Originally posted by 89s1
Much like the picture in his signature nonlinear must see everything as black & white.

I honestly don't see whats so hard to understand, but he has a hard time with lots of things that seem pretty logical to me... :dunno:

dude, seriously, why do you always have to turn everything into personal attacks on my character? am i really being such an asshole, or such an idiot, that you have to constantly act like an 8th grader? grow up dude!

i'm an accurate and precise guy, and i want my tires inflated properly. i also want to know WHY i'm inflating to a given pressure. if it's too much for you, you don't have to read the thread. geez!

:nut:

[GTS4tw]

Originally posted by nonlinear


yea i've never worn through a set of tires enough to see the long-term wear patterns. but i've always ran at maximum recommended inflation. :dunno:

i have yet to see a convincing argument of why to run below max inflation. i've also read quite a bit about why under-inflation is bad. :dunno:

I put on at least 60000kms a year with my tires just below max inflation at COLD pressure. Trust me when I say max inflation is totally fine, although as I said before you might want to run them a bit below for better grip in the winter. Max inflation according to the sidewall will get you perfect wear on any tire I have run, including summer and winter goodyear, bfg, toyo, falken, golden fury, etc, etc. To say that max inflation will cause a blowout like a balloon being overinflated is absolutely false. Tire

[ercchry]

Originally posted by nonlinear


yea i've never worn through a set of tires enough to see the long-term wear patterns. but i've always ran at maximum recommended inflation. :dunno:

i have yet to see a convincing argument of why to run below max inflation. i've also read quite a bit about why under-inflation is bad. :dunno:

so.... you have no proof that your over inflated tires are the way to go?

you see i on the other hand go thru a set of tires every month... some times twice... and i can tell you that tire pressure greatly effects wear and traction...

i am trying to find the sticker that benz's have under the gas lid... but i can not seem to find the one i am looking for, basically it tells you the size of tires on the car and what psi to run the tires at according to the speed the car is traveling.

this question is not as clean cut as you are trying to make it out to be, im sure if you actually looked hard enough you would be able to find information on how these pressures are figured out, area of tire, weight of vehicle, etc, etc

[nonlinear]

Originally posted by 89s1
Inflating to maximum pressure leaves less room for expansion of the air as it comes up to temperature. Get it? Set it to max cold, it quickly goes above max when driving long distances or on a nice hot day.

:facepalm: :facepalm: :facepalm:

once again, just so we're all on the same page.

the maximum recommended inflation pressure IS a cold inflation. this implicitly "accounts" for the small increase in pressure you'll see at operating temperature.

[89s1]

fuuuck.:facepalm: :facepalm: :facepalm:

[ercchry]

Originally posted by 89s1
Inflating to maximum pressure leaves less room for expansion of the air as it comes up to temperature. Get it? Set it to max cold, it quickly goes above max when driving long distances or on a nice hot day.

THANK YOU!

see this guy understands the point i was trying to make.... get it now gts4tw?

[nonlinear]

Originally posted by ercchry


THANK YOU!

see this guy understands the point i was trying to make.... get it now gts4tw?

what? you can't be serious.

[ercchry]

Originally posted by nonlinear


:facepalm: :facepalm: :facepalm:

once again, just so we're all on the same page.

the maximum recommended inflation pressure IS a cold inflation. this implicitly "accounts" for the small increase in pressure you'll see at operating temperature.

what is cold though? -10? thats pretty cold.... air will be much more dense at -10 then... lets say.... +30?

[Team_Mclaren]

people inflate their tires to 40PSI???:rofl: :rofl: :rofl:

[GTS4tw]

Originally posted by ercchry


THANK YOU!

see this guy understands the point i was trying to make.... get it now gts4tw?

No. you are wrong. If its too hard still then I give up.

[nonlinear]

sorry, but you guys are being idiots :poosie:

http://www.tirerack.com/tires/tiretech/tirespecskey.jsp

Maximum Inflation Pressure

A tire's maximum inflation pressure is the highest "cold" inflation pressure that the tire is designed to contain. However the tire's maximum inflation pressure should only be used when called for on the vehicle's tire placard or in the vehicle's owners manual. It is also important to remember that the vehicle's recommended tire inflation pressure is always to be measured and set when the tire is "cold". Cold conditions are defined as early in the morning before the day's ambient temperature, sun's radiant heat or the heat generated while driving have caused the tire pressure to temporarily increase.

For the reasons indicated above, It is also normal to experience "hot" tire pressures that are up to 5 to 6 psi above the tire's recommended "cold" pressure during the day if the vehicle is parked in the sun or has been extensively driven. Therefore, if the vehicle's recommended "cold" inflation pressures correspond with the tire's maximum inflation pressure, it will often appear that too much tire pressure is present. However, this extra "hot" tire pressure is temporary and should NOT be bled off to return the tire pressure to within the maximum inflation pressure value branded on the tire. If the "cold" tire pressure was correctly set initially, the temporary "hot" tire pressure will have returned to the tire's maximum inflation pressure when next measured in "cold" conditions.

[89s1]

Originally posted by Team_Mclaren
people inflate their tires to 40PSI???:rofl: :rofl: :rofl:

about 32, but no higher than 35 here, and my max cold press. is 40 psi on the sidewall. :)

[alloroc]

Sugarphreak had it dead on.

Manufacturers test and come up with these pressures to give slight under steer in most conditions. I personally find the factory recommended pressures 2 to 5 psi too low I get better steering response and more even wear with more pressure because of my slightly more aggressive driving.

Edit: back in the day when I used to autoslalom we would draw a chalk line across the sidewall from the tread to the rim. When exactly half of the line was worn off you knew you were in the ballpark for inflation and then only had to tweak the front/rear pressures for the right amount of under/oversteer.

Anyways ...
If you want to stay with recommended ratings on aftermarket tires use the percentage rule.

Say the OEM tire max is 35 psi and the recommended pressure in the vehicle manual is 30 psi for that tire. The pressure is 85.7% of the max pressure. I buy some aftermarket tires with a max pressure of 44 psi you should fill to about 38 PSI.

[89s1]

Originally posted by alloroc
Sugarphreak had it dead on.

Manufacturers test and come up with these pressures to give slight under steer in most conditions. I personally find the factory recommended pressures 2 to 5 psi too low I get better steering response and more even wear with more pressure because of my slightly more aggressive driving.

Anyways ...
If you want to stay with recommended ratings on aftermarket tires use the percentage rule.

Say the OEM tire max is 35 psi and the recommended pressure in the vehicle manual is 30 psi for that tire. The pressure is 85.7% of the max pressure. I buy some aftermarket tires with a max pressure of 44 psi you should fill to about 38 PSI.
:) :thumbsup:

[nonlinear]

Originally posted by alloroc
Sugarphreak had it dead on.

Manufacturers test and come up with these pressures to give slight under steer in most conditions. I personally find the factory recommended pressures 2 to 5 psi too low I get better steering response and more even wear with more pressure because of my slightly more aggressive driving.

Edit: back in the day when I used to autoslalom we would draw a chalk line across the sidewall from the tread to the rim. When exactly half of the line was worn off you knew you were in the ballpark for inflation and then only had to tweak the front/rear pressures for the right amount of under/oversteer.

Anyways ...
If you want to stay with recommended ratings on aftermarket tires use the percentage rule.

Say the OEM tire max is 35 psi and the recommended pressure in the vehicle manual is 30 psi for that tire. The pressure is 85.7% of the max pressure. I buy some aftermarket tires with a max pressure of 44 psi you should fill to about 38 PSI.

:thumbsup:

i like how you are thinking, however I think that the auto manufacturer's recommended value is only appropriate for the OEM tires. also, 85.7% in one tire doesn't necessarily equal 85.7% in another tire.

[YamahaV8]

^^^
It also says right in your quote there that the maximum tire pressure should only be used if the vehicle's recommended pressure calls for it. Your own quote contradicts your opinion and makes you look like the idiot. The max pressure on the side of the tire is not the recommended pressure for the tire. It is a max safe cold pressure that the tire can handle without exploding going over a huge pothole. I challenge you to email any tire manufacturer and see if they recommend the max pressure on the sidewall.

[89s1]

Originally posted by YamahaV8
^^^
It also says right in your quote there that the maximum tire pressure should only be used if the vehicle's recommended pressure calls for it. Your own quote contradicts your opinion and makes you look like the idiot. The max pressure on the side of the tire is not the recommended pressure for the tire. It is a max safe cold pressure that the tire can handle without exploding going over a huge pothole. I challenge you to email any tire manufacturer and see if they recommend the max pressure on the sidewall.

Before he edited he simply agreed with him, but then realized his borderline troll thread might die off, so he changed it up to keep the feeding frenzy going.

I think it's about time nonlinear goes onto the ignore list...

[alloroc]

Originally posted by nonlinear


:thumbsup:

i like how you are thinking, however I think that the auto manufacturer's recommended value is only appropriate for the OEM tires. also, 85.7% in one tire doesn't necessarily equal 85.7% in another tire.

It also works out because of sidewall stiffness. For example Kumhos normally have softer sidewalls and you don't want to be running 32 psi in a set of Kumho SPT's with a max pressure of 50 or 51 PSI.

[nonlinear]

sorry, off topic

[ercchry]

Originally posted by nonlinear


:thumbsup:

i like how you are thinking, however I think that the auto manufacturer's recommended value is only appropriate for the OEM tires.

most cars (german) give you two psi ratings for a certain size of tire, not brand... just size, one for regular load, another for heavy loads

[89s1]

Originally posted by 89s1


Before he edited he simply agreed with him, but then realized his borderline troll thread might die off, so he changed it up to keep the feeding frenzy going.

I think it's about time nonlinear goes onto the ignore list...

Worried I won't see his posts he resorts to PM's. He is a fucking troll... Desperate for any attention he can get. :rofl:

[nonlinear]

Originally posted by 89s1


Worried I won't see his posts he resorts to PM's. He is a fucking troll... Desperate for any attention he can get. :rofl:

dude, you have serious problems. i went to PMs because it's off topic for the thread. but since you are doing everything in your power to discredit my character, i will post said PM:

subject: why all the hate?


Originally posted by 89s1


Before he edited he simply agreed with him, but then realized his borderline troll thread might die off, so he changed it up to keep the feeding frenzy going.

I think it's about time nonlinear goes onto the ignore list...

please, add me to your ignore list; i could care less if you read my posts. aside from your inane infantile banter, you contribute nothing to this forum. i've tried to treat you with respect and maturity, and overlook your baseless personal attacks on my character, yet you continue to act like a fucking 13 year old kid trying to fit in at school. please, put me on ignore now so i don't have to deal with your crap anymore.

[FraserB]

I might be alone in this but I don't use either number. the tires I ran were aggressive mud terrains and I used the chalk test to find the best inflation.

Lay a stripe of chalk or marker across the tire and drive a few hundred feet on dry pavement. Observe how the chalk is wearing and adjust accordingly until the chalk wears evenly across the tire.

[jljhlhl]

Originally posted by FraserB
I might be alone in this but I don't use either number. the tires I ran were aggressive mud terrains and I used the chalk test to find the best inflation.

Lay a stripe of chalk or marker across the tire and drive a few hundred feet on dry pavement. Observe how the chalk is wearing and adjust accordingly until the chalk wears evenly across the tire.

Best way to determine optimum pressure. Load range E light truck tires will say maximum 80psi generally, but you would never run them that high for everyday driving. I run mine at 44psi and could still drop them down to the recommended 35psi without much change in tirewear. The chalk method works best to determine the best psi though.

[Sugarphreak]

...

[scat19]

Front 32PSI rear 38PSI.

Manufacturer specs.


I would never inflate to maximum PSI.

^^Sugar are you serious? IMO that's retarded. You lose power steering and instand acceleration if someone comes up behind you too fast, or you have to avoid an accident in front of you. IIRC the engine doesn't use gas when it looses RPM while decelerating.... Just the blip at idle to catch it from dying.

[nonlinear]

so yesterday I filled my tires to about 44 psi when they were hot (so my cold inflation pressure was probably high 30s or 40 - just an estimate). on the ride in to work today, i noticed that the car handled quite different, and not as good as when the tires were at 30 psi. i think i'll bleed them to about 35 psi and see how things are then. for me, i'm trying to balance fuel economy tire life, and handling. just gotta find that sweet spot, you know?

[nonlinear]

Originally posted by Sugarphreak


The biggest thing you are overlooking is that vehicle weight plays a bigger role in your inflation pressure. One tire can go onto many cars, cars which all have different curb weights. If you have a light weight car, usually your reccomended tire pressure is less then a heavier car using the exact same tires.


well put. this is the best explanation/argument i've heard here or on the net for using the car manufacturer's recommended psi.

[alloroc]

Originally posted by scat19
Front 32PSI rear 38PSI.

Manufacturer specs.


I would never inflate to maximum PSI.

Wow!

There is a perfect example of how manufacturers ensure understeer with tire pressure.

[powerslave]

When I had my winter tires installed, I noticed quite a difference in the way the car handled (read: it handled like crap). Once I got home, I took a look at the tire and noticed the shop inflated all four of them to 45psi! Quite a difference from 32 psi that I usually run (and which is recommended by the manufacturer).
Needless to say, I bled the extra air and things are back to normal again.

[Sugarphreak]

......

[bituerbo]

My Audi has a chart, indicating the number of passengers and what the correct front/rear pressures should be. 34F 36-38R is usually where I'm at, depending on the type of driving I'm going to be doing.

[codetrap]

So.. the general verdict is run your tires at the Car manufacturers recommended PSI plus a pound or 2 for better economy. Not to the run them at the max pressure indicated on the side of the tire.

Makes sense to me. 36F & 42R for the Jetta, and I usually run at 38 + 45. Tires max out at 50.

On a side note, it's interesting to see nonlinear pull a full 180 in his arguments in this thread. Learning is good!