oops, I sent this from my non-registered a2-16v list email address
On 7/1/07, Chad Rebuck <[email protected]> wrote:
> Thanks Holland, Josh, > > My alignment specs are stock, nothing special done with them. The > limit of my suspension mods is a shine street suspension w/ bar bolted > to the rear axle and bilstein hd absorbers. I started using 40 cold > psi in the fronts yesterday morning (based on some quick reading I had > done) but i think that may have been too much because my car would > understeer quite a bit bearing the end of my 30 minute session. I > dropped it to 36 hot and that was better but I did see the tires get > scuffed up a significant way down the sidewall. I didn't chalk or > check the temp but I'll do that next time just for fun. I'll surely > start with front 39-40 / rear 34-35 front hot pressure next time I > auto-x. > > Auto-x was a lot more fun than I thought it would be. I had > previously only gone to Sebring to run the track a few times with bmw > club and porsche club. Auto-x was a lot cheaper and I learned quite a > lot. Too bad one of those cones took out my plastic fender liner on > the front right tire :) > > On 7/1/07, DocWyte <[email protected]> wrote: > > 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 > > > > >
