usccharles

Hello,

Have been searching and reading up on everyone's track day tire pressure recommendations across various tire brands. Gotta really appreciate forums such as RL for the wealth of invaluable information on such topics.

One question though, I have C4 GTS going from the Pzeros to a fresh set of Cup 2s and getting alot of my tire pressure information from the GT3 folk. Can I assume that the pressure guidelines for GT3 and other 991 models are relatively all same to my GTS or should I be making adjustments for reasons I do not yet understand?

I'm sure there is alot personal preference and trial and error involved, as even the recommendations I read are each all different to each other, but just curious if different models across the 991 line also inherently changes things.

Thanks

C

008

Yes, within a range. Use it as a guide and fine tune from there. All wheel drive may dictate a different front to rear ratio as an example. Your alignment will also play a large role. Tracks with banking, etc. On my C2S with a track oriented alignment I run 35psi all around with MSC2s at most tracks.

Vise

Same here, I run 35-36 hot on my 991 GTS with Cup 2s and a moderately aggressive alignment. I normally start around 28-29 cold and then adjust as they warm up.

MrFarenheit

What I found most helpful was to pick one pressure and then bleed whatever was needed to maintain that pressure as constant as possible all day long. So if I start at say 32/35 and come off the track at say 36/44 then I would bleed back to 32/35. Immediately. While the tires are still hot. This means starting the next run cooler/lower at say 30/33. But within a few laps I'm right where I want to be. Track and tires tend to get warmer as the day goes along, you are always bleeding, but typically less and less each time.

What I learned, by running more consistently, it helped me understand how pressure affects feel, grip and handling. Anything above 40, you start losing traction fast. I always thought this was tires getting hot, and soft, when really it was pressure.

Then once I got used to how the tires work at that one setting, when I would make a change it was really noticeable. Eventually I got it dialed in to my preferred balance, that made the car feel and handle the way I wanted. And because of the way I got there I know why.

stout

^ Good advice above.

I target 35/36 hot all around, bleeding in 2psi increments as needed to get and stay there. I find that anything past 38-39 and I already feel a drop-off, anything under 33-34 means the tires aren't getting up to temp.

erko1905

+1 for 35 hot (which is somewhere between 26 to 29 cold, depending on ambient and track temp) -- PS4S

John Mclane

Pzero is far more sensitive to high temps and to put salt on the wound, it reaches high temps quickly and will let go on a curve wo a hint, just snap on you. POS of a tire.

Cup2 increases temps much slower and won’t snap even at moderately high pressures (40 give it or take-above that it won’t hold as well).
I run 32/34 hot, which quite low cold, about 22-24. Even in the event of snapping, is far more controllable.

BTW, I use the Cup2 in my DD, wo an issue. Swapping to Alpins next week, after all Chicagoland does get frigid...

PS - remember to check the rear pads. Although most of the breaking is done with the fronts, the rears get toasted bc of the PSM. Mine lasted for about 6k miles, 3 track days. Front pads are about 80%(!)...

randr

32f 34r hot (or 32 hot all round - depending on circuit).

randr

and this



note road driving and wet weather

randr

and this (all of these are direct from Michelin and relevant for MPSC-MPSC2)

John Mclane

This is awesome info, thanks!!!

4pipes

Also, I’ll add, get used to the TPMS throwing a warning all session long in the 991.2 after you’ve bled off 5 PSI.

usccharles

Thank you so much for all the useful information. HAHA but see now you guys are throwing a curve ball. all this time ive been searching Cup2 track pressures i though 29/33 psi were about the consensus, but seems like the gentlemen in this thread like near about of 35 psi, all around even! i have alot of track time and needed experience to sort through all this! thank you though!

one question, why decide to go same pressure all around? if the car is rear weight biased? i would assume you would want less psi in the front?

currently i'm going to try 32/35 hot and work my way back and forth to see whats right for me.

Please is there a way to turn this TPMS warning off!? i get so distracted when this happens.

thank you all

usccharles

mr Randr these infos are so awesome. Thank you.

Need4S

991 turbo, MPSS, 35/39 hot seems to work well.