Is my tire pressure okay?

[chachacha28]

245/255 MPSS's at 35 psi cold(ish) all around. My wheel is like, 1/4 inch from hitting the ground. should i run 40 all around?

this is also with 3 passengers, so there is at least 500lbs of extra weight in the car.

here is a picture of my car static, same ride height, and normal looking sidewalls. (the picture is pre-fenderpull, but ride height is the same)

[Dackelone]

I run 225/255's PS3's... I run 2.3 bar and 2.8 bar pressures(front/rear).

[chachacha28]

Originally Posted by Dackelone

I run 225/255's PS3's... I run 2.3 bar and 2.8 bar pressures(front/rear).

I really feel like i should bump up the pressure a bit. My sidewalls are visibly darker on the side than they were when they were new. I cant tell if its from rubbing of rolling over, this picture makes me lean towards the latter though. It just doesnt look safe, or fast.

[Dackelone]

yea... your right front tire does look like its folding under the wheel! Try bumping up your pressures - at least when you hit the Ring!

[chachacha28]

what do you think i should run, 40 psi cold? or should i bump it in lower increments. Ive heard of people putting chalk or shoe polish on their tires, should i give this a go? what exactly would i be looking for? The way it sounded to me, you rub the stuff on the sidewall, do your lap, and see how far it rubbed off. If there is no polish left on the sidewall, it means it rolled over (like mine did in that picture) and you need to increase pressure. do i have that right?

[Focusedintntions]

OP w/o running camber plates regardless of what psi you run you're going to roll over the tires. PSS don't like to run more than 38-39 psi hot otherwise they get very greasy quick. Those have been my findings with tracking the car.

[GaryS]

FWIW I use 36 lbs cold for street if I measure in the morning, 38 lbs cold if I measure in the afternoon. For track, I used 38 lbs hot. I don't do autocross, but I guess that would be 38 lbs cold. I never have rear seat passengers, but if I did, I would add 1 lb for each person. I'm thinking you probably need more front camber for track and autocross.

edit: haha Focused always types faster than I do.

[chachacha28]

Originally Posted by Focusedintntions

OP w/o running camber plates regardless of what psi you run you're going to roll over the tires. PSS don't like to run more than 38-39 psi hot otherwise they get very greasy quick. Those have been my findings with tracking the car.

my vorshlag camber plates are maxed out (and i have the M3 control arms), so i dont think a lack of camber is an issue. there are a few other pictures in my garage that you can take a look at (also has all my mods). Im still on stock sway bars if that matters.

[Focusedintntions]

Ah sorry didn't take a look at your garage....I wonder how much of the perceived "issue" is just the angle of that photo. You probably have a bit of rollover which is normal. As long as the rim isn't hitting the ground I think you're fine. There have been lots of us that run those tires at those pressure and have never had an issue.

[chachacha28]

Originally Posted by Focusedintntions

Ah sorry didn't take a look at your garage....I wonder how much of the perceived "issue" is just the angle of that photo. You probably have a bit of rollover which is normal. As long as the rim isn't hitting the ground I think you're fine. There have been lots of us that run those tires at those pressure and have never had an issue.

I was wondering the same thing, as the issue doesnt seem to be too bad in any of the other pictures.

I might give this a try though http://mgaguru.com/mgtech/tires/sp101.htm

[Dackelone]

Originally Posted by ezeedee

what do you think i should run, 40 psi cold? or should i bump it in lower increments. Ive heard of people putting chalk or shoe polish on their tires, should i give this a go? what exactly would i be looking for? The way it sounded to me, you rub the stuff on the sidewall, do your lap, and see how far it rubbed off. If there is no polish left on the sidewall, it means it rolled over (like mine did in that picture) and you need to increase pressure. do i have that right?

You got the correct understanding of marking the sidewalls for "roll over". Just put a small one or two inch strip of chalk/shoe polish on the sidewall (vertically) then do some "cornering testing" and see how much is left on the sidewalls.

Also... don't go by that Karousel 'Ring photo... a lot of race cars loose tires in there because they go in too hot and pull the tire off the wheel. Its easy to do. That is why you can't go all that fast thru the 'Ring's Karousel section. My buddy with the GT3RS cup cars were loosing rear tires at the last Ring race. No one seemed to know why. Just that the RR would go flat or get cut.

I would start at 2.4/2.9 bar and go up in 0.2 bar pressures/increments front/rear. See how it feels and see how much roll over you get. Like I said I run 2.3/2.8bar for the street - mostly bc I drive very fast and want "good feed back" at higher speeds (150~180 mph).


Dack

[Evice]

Only way to make sure if your tires are OK is to measure their temperature, preferably in hot pits. Plus I do not see that much of trouble in the picture. That's somewhat expected..Esp. at that location.