mikesh

Hey Guys,
I have an autocross on sunday, and was wondering what tire pressures you guys run. I have an '05 c2 w/ 19"s.

I did a search and it seams people run a bit lower pressure for the track, but in the past, (I've done a couple years of autocross in my GTI), I've always increased pressure a few lbs to keep the sidewalls from rolling over. What do you guys do?


Thanks.

mike

MJones

Increase the front pressure by 4#, that will help prevent the scrubbing of the outer edge.

cole328

I like 36 / 38 HOT

eljeffo64

same for me

equiraptor

The problem is, "hot" is hard to reach in autocross, and how fast the tires will reach it depends on a wide array of things, such as course surface, the course, the ambient temperature, how much time you have between runs, etc.

Given the short sidewalls and the higher factory pressure on the 911, I'd say start with around 5 psi over what the car has on the street.

Mike, how much effort are you interested in putting into finding the right tire pressure? If you want, you could use the chalk / shoe polish trick. Put a line of chalk or shoe polish around the tire, going across the tread and up the sidewall. You can see how far over the tires are rolling by how far up the sidewall the chalk is worn off.

A more precise way to find the right pressure is with a thermometer. Check temperatures as soon as you're off course - the sooner the better. You want an even temperature across the tread. If the edges of the tread are cooler, the tire has too much air. Let some out. If the middle is cooler, there's not enough air.

Or you could just push in a few more PSI and enjoy your runs.

Edgy01

It depends. There are so many variables there in setting TPs that only you can determine what works best for your surface conditions, car setup, tire type, etc. This is a fairly complicated and well-guarded secret in many racing circles and the only way you can figure it out is through your own experience. Good luck!