Alot is based on how much camber you're running as well. In general 39-40psi in the front hot is what you want to shoot for, 34-35 in the rear.
--- Holland Phillips <[email protected]> wrote: > Chad, > Without knowing what your suspension setup is (both > hardware and > geometry), including wheel width and offset, > I'll give you a couple of "rules of thumb". With > front wheel drive, > you generally want a 5 psi spread front to rear (+5 > psi in the front). If possible, replace the air in > the tires with > dry nitrogen. Here in San Jose, a lot of tire > shops, > including Costco, use nitrogen when installing new > tires. Your > pressures won't increase as much when the tires > heat up, which can be a real advantage on the track. > Tires with a > speed rating of VR (149mph), or greater, > the max pressure rating (molded into the sidewall, > down near the > bead) will usually be 40-50psi. I't's not a good > idea to exceed that, and I've never had a set of > tires that required > going above the max to get them to work right. > The last couple of sets of tires I've had on my '92 > GTI 16V (Toyo > Proxes T1s & GoodYear F1 GS-D3, 215/40-ZR-16) > have worked well with 36 psi/front, 31 psi rear. > That's for very > hard street driving. If I took the car to the > track, I'd > probably end up raising the pressures to maybe 40 > psi/35 psi. The > "real" way to determine if you're pressures > are correct, is to take temperatures across the > tire's tread surface > with a infrared temp gauge after running a few > fast laps on a road course, or after a run through > an auto cross > course. Assuming your suspension setup is close > to correct, if your tire temps are consistent across > the tread, then > your pressures are about right. If they're higher > in the center of the tire, then the pressure is too > high. If they're > higher toward the side walls, and lower in the > center, > then the pressure is too low. The same method can > be utilized to set > up the suspension. If the tire temps tend to run > higher toward the outside of the tread, you probably > need more > negative camber. If the reverse is true, then dial > in > less negative camber. Keep in mind that all this > stuff is inter- > related, so you only want to change one thing at a > time, > make a run, check the temps, then make another > change accordingly. > > --Holland > [email protected] > > > On Jun 29, 2007, at 2:07 PM, Chad Rebuck wrote: > > > For 195/50-15 performance tires (not racing > compound) what pressures > > should I use for the track? The driving time will > be limited to 15-30 > > minutes at a time. I think its more of an > extended auto-x instead of > > all out driving at a racetrack. What method do > people use to come up > > with the right pressure? > > _______________________________________________ > > a2-16v-list mailing list > > [email protected] > > > http://mail.a2-16v.com/mailman/listinfo/a2-16v-list > > For list archives, see listinfo link above. > > _______________________________________________ > a2-16v-list mailing list > [email protected] > http://mail.a2-16v.com/mailman/listinfo/a2-16v-list > For list archives, see listinfo link above. > ____________________________________________________________________________________ Bored stiff? Loosen up... Download and play hundreds of games for free on Yahoo! Games. http://games.yahoo.com/games/front
