I took my IROC to an autocross school on Sunday. I think I over-inflated my tires. Unfortunately, the format made it difficult to adjust them later on and I ended up living with it for the whole day.

I ran with:
44 psi on the front
42 psi on the back

What do you guys run?

 

Depends upon the tire, when I was auto-xing I was using SZ50's 39 PSI in the front, 38 rear. Using GSCS Dot racing tire, on warm days I started with 28/29. Cold days 25/26.

 

you can tune with some shoe polish too. it's basic, but better than nothing. put white shoe polish on the sidewall/shoulder/outermost tread on each tire in a 3 or 4 inch area. you want to maximize your contact patch without rolling the tire over. after each run, you can read the telltale signs of the worn off shoe polish.

If you have access to a pyrometer, that's an invaluably tool. at least it tells you how the tires were doing in the last corner aim for an even temperature distribution across the tire.

Clem

 

Thanks for the replies, guys. It sounds like I should reduce my initial pressures and take some shoe polish with me at this Sunday's event. If I learn anything useful, I'll report back.

 

Shoe polish works well, and is better than nothing at all.
As clemsparks stated earlier use the worn off edge of the polish to determine whether or not you need to inflate or deflate your tires for maximun contact patch.
The general rule is: 2lbs of air = 1/2" of 'edge' movement.
If you have any trouble 'reading' the tire, ask one of the autocross veterans to help. I'm sure they've done it before, and most are happy to help out newcomers
Good Luck, and let us know how it went

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Redbird
Bayou Motorsports
87 Firebird-Daily Driver/Autocrosser
84 Z28-Full bore Autocross car
Delta Region SCCA
#00 C Prepared

 

I run close to 44 psi front and 36 psi rear in my Kuhmo Victoracers (265/45/16) and this seems to work well. It really depends on what tire you are using.

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87 Formula 350 13.94@96.67
98 Z28 1LE 13.15@107.59
1LE Owners Association