[FASTFATBOY]

First time on r comps.

The front end is chattering in the corner, get on the gas and it fixes it cant carry any entry speed because of it.

Tires are BFG R1's, pressures to start are 30F 26 R, end of session 34F 33R.

I took the rear spring rubbers out and lowered the rear. The ass end was all over the place, this helped a bunch and dropped 3 seconds off the lap time.

Go up or down on pressure or what?

You enter the corner, the car starts to push and the tires chatter, skip, gas pedal pedal helps it.

All input welcome.

My new best is 2:02 at NOLA.

[Blainefab]

With Toyo/Hoosier/Yokohama, starting cold pressures of 21-26psi are typical. YMMV. Too much and they'll feel nice and crisp at turn in, but start sliding after a few laps and turn to grease. When pressures are right, turnin may feel soggy, even after they are up to temp, but the grip will be consistent for the rest of the session. A tire pyrometer is a good tool to have in your box, but like a lot of things there is a learning curve to get thru before it's useful.

Sidewall rollover is less useful a tuning tool for race rubber, they typically have much stiffer sidewalls than a street tire and won't roll much in the useful range of pressures.

[Interceptor]

With Toyo/Hoosier/Yokohama, starting cold pressures of 21-26psi are typical. YMMV. Too much and they'll feel nice and crisp at turn in, but start sliding after a few laps and turn to grease. When pressures are right, turnin may feel soggy, even after they are up to temp, but the grip will be consistent for the rest of the session. A tire pyrometer is a good tool to have in your box, but like a lot of things there is a learning curve to get thru before it's useful.

Sidewall rollover is less useful a tuning tool for race rubber, they typically have much stiffer sidewalls than a street tire and won't roll much in the useful range of pressures.

I thought tire pressure was low as well, I start at 36-38-ish. I thought the Z28 shaped right up after going from 32 to 36. What should tread temps be, and how do you know? Our cars are pretty heavy out front, don't they need more air?

[ReEntryRacer]

With Toyo/Hoosier/Yokohama, starting cold pressures of 21-26psi are typical. YMMV. Too much and they'll feel nice and crisp at turn in, but start sliding after a few laps and turn to grease. When pressures are right, turnin may feel soggy, even after they are up to temp, but the grip will be consistent for the rest of the session. A tire pyrometer is a good tool to have in your box, but like a lot of things there is a learning curve to get thru before it's useful.

Sidewall rollover is less useful a tuning tool for race rubber, they typically have much stiffer sidewalls than a street tire and won't roll much in the useful range of pressures.

I thought tire pressure was low as well, I start at 36-38-ish. I thought the Z28 shaped right up after going from 32 to 36. What should tread temps be, and how do you know? Our cars are pretty heavy out front, don't they need more air?

I find myself disagreeing with Blaine for the first time... probably at my peril (IMG:http://www.frrax.com/rrforum/style_emoticons/default/rolleyes.gif) Perhaps our tracks up here in the Great White North use a different asphalt or something, but I also find the starting and finish pressures too low.

With me in it, my car weighs 3400 lbs. and I use Hoosiers and Continentals (also Hoosiers) and a calibrated pressure gauge. I use dry N2.
I've kept records for many years using pyrometers to take multiple readings across every tire, at every race. Depending on OAT and track temps, the fronts need 35 to 37 PSI "cold" and will end up at 42 to 45 hot. This varies of course, with all kinds of variables at play, but my data is as real and as carefully plotted as possible. I never get chatter, and I get very good tire life. Oh, and I guess the pavement isn't all that different as these number are valid for PIR (OR) and Laguna Seca (CA) too!