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Whisper wrote:

Volones wrote:but I have not read anything about inflating them to the tire manufacturer's max being dangerous at all.

It's not recommended to inflate to the max pressure indicated on the sidewall, because as tires heat up during driving the pressure increases. If it goes too far past the maximum, the tire's durability decreases, and you'll also likely cause uneven wear. Also I imagine overinflated tires cause more suspension wear, since they're no longer soft enough to absorb a lot of the road surface imperfections.

in all my years hangin around mechanics garage's ive never heard of this...why would the factory post a psi rating on a tire if they didnt expect the consumer to fill to that amount...companies perform hundreds of tests to determine things like this..mind you im sure your right about the wear on suspension and what not...every car ive ever had (on my 8th now) ive always inflated the tires to spec, and have never had a problem

It's not spec. It's maximum (I'm guessing warm tire) pressure that they don't recommend exceeding. I run my tires at 36 psi for daily street commute. There's really no reason to overinflate your tires.

The tire pressure on the door is for the stock tires on the stock rims. You change from that you don't have to follow it. Volones hit it on the head.

Whisper is right about not exceding what it says on the sidewall.

More pressure and a firmer tire will get you better milleage and steering responce. It's also I'm not too sure about wear tho, you have less of a contact patch, which would affect you breaking distance, but i'd see a lower pressure wear out more since there's more rolling resistance from a larger contact surface to create more heat to cause it to wear faster, but on the other side, a smaller contact area from lower pressure would have more weight on it, so that's probably a null-void point.

In the end, run your tires as you wish. Don't listen to the door sticker if you don't want to, but go by the tires. You can run max PSI for what the tires say, but it would be best to test the pressure when the tires are warm, or when cold, go a few PSI (2-5) below since they will increase when they warm up. Same as the temperature changes. There's the jokes about summer air and winter air, but it does have a good affect. You put air in your tires, you have a set amount of air molecules in your tires (given none escape from leaks, etc). When it gets cold, the air molecules get closer together, more dence, you lose pressure. On hotter days, the molecules spread farther apart, your pressure increases.

That's why their touting nitrogen now. We use it on aircraft but it is more an issue of tire fire from hot wheels than anything else. I've never inflated mine to over 32psi as the centre tread seems to wear out then. 36 to 40+ psi sounds a little high to me for the weight of our car. Interesting post.

Daninski wrote:I've never inflated mine to over 32psi as the centre tread seems to wear out then.

Exactly, some tires are effected differently from pressure than highers, even if your not inflating it past the manufacturer's specs. That's doing to have to be a judgement call to the owner/driver. But no everone is competent to perperly maintain and monitor their vehicle, so i'm sure that number on the door sticker is a safe guideline for everyone. Even when you go for a oil change, most if not all places will check and adjust the tire pressure. I usually have to tell them to NOT touch my tires.

BTW, my Komho Mx's, inflated to close or at 50psi (of a max of 51) wore evenly, even with that the fact that I'm lowered, although I have camber bolts, I was told to expect some camber-like wear.

I've posted this before:
If you want maximum tire patch, and even wear, get a good contact thermometer, and drive for a while, including fast cornering. Stop, and check the temp of the inside edge of the tread, middle, and outside. If the inside is cooler, inflate a little, and vise-versa. Keep doing this until the temps are the same. Autocrossers will tell you that 40 psi is a good place to start.

I have 205/40/17 falkens and it says 40 max on the sidewall; I run mine at 35 as I find 40psi a bit too bumpy

wow after autocrossing this weekend I learned ALOT about tire pressure!

especially since it was 110 degrees on saturday when we were running

Well...


Did anyone mention my great method?

lol I didn't, I'm ignorant and lazy... and plus I don't have a contact thermometer! where can I buy one? I am pretty sure my psi was fine since my tires were wearing evenly...