jvecchi

I'm looking for some input. I have '15 991 GT3 that I track at Pittsburgh International. The car is as from the factory, other than a Sharkwerks bypass exhaust. I'm running Sport Cup 2 tires.

I set the tire pressures at 29F/33R cold. After a few laps the dash says the tires are at around 38F/43R, and the car seems to 'skate' a bit, with just a hint of understeer. What tires pressures hot would you suggest?

Also, what about suspension settings? Sway bar adjustments? Anyone have suggestions? Any input would be greatly appreciated.

golfnutintib

26/29 cold

RobC4sX51

How about a C4s w P Zero tires? I was at the track last wknd (Putnam Park Road Course) & I also had some slippery tires after warm up. Started w 32/36 which I read here some where was a good place to start.

cajerseyboy

I spoke with a representative from Michelin at the Werks reunion In Carmel. He said to in them between 32-38 hot.

jvecchi

Thanks for the intel.

Randyc151

I've used up 4-5 sets of Cup2 tires on the track, and done a lot of data logging.

It's tough to suggest what tire pressure to "start cold at" because of varying weather, but generally I start out at 26 all around and go out at 6/10 for a couple of laps in the morning to really warm the tires, especially slower on sharper turn in corners. Don't want to roll over the sidewalls!! When TPMS show the tires are up to 32-33, I come in and manually readjust them to 29 front/ 31 rear hot. This is the ideal pressure for the remainder of the day!! (TPMS is only accurate to about 2-3 PSI, which is a world of diff on these tires, especially at higher speeds like VIR. Use your handheld air gauge to dial it in.)

Above 35 PSI, these tires are nearly worthless. 29f/31r will give you max grip with no rollover, and Michelin had a PDF out for a while saying to keep the tires under 32 PSI that has since been pulled. If you are "going for it" then continuously readjust to 29/31, but if you are just out turning laps for fun, then just keep them under 35.

golfnutintib

i agree cup 2 grip falls off precipitously over 35-36 psi when pushing on track

Jcolombotos

Im out west Laguna Seca


PSC2
Cold
Front 23
Rear 24

two warm up laps, then go get you some! lol

Hot
Front 30
Rear 32

jmartpr

I agree to shot for 30-32 psi hot temps...BTW, if you use the circuit mode on your GT3 it wont accept 26 psi. Go out cold at 27 psi which is the minimum the system will accept and when you go above 33 psi go in check pressure with a hand held gauge and bleed accordingly.
Also, I have found TPMS to be a bit more accurate that the mentioned 2-3 psi difference, at least on my car. It's also a good early warning if you do get a flat.

mdrums

Michelin tire engineers say do not drive below 27 psi. GMP Motorsports held a on line Q&A session and this was discussed.

So I go out at 28front 30 rear and adjust from there keep hot temps around 32-34 front and 34-36 rear. For my track, Sebring, and alignment-1.7 all around seems to wear tires mostly even.