II have mich PSS on both my 911s. I run 29F 32R cold on the 2007 GT3. Same as running Pirelli corsa.
Ran 33F 36R on c4S but not longer track that car.

 

[QUOTE=Hatzenbach;3854847]Are these Michelin SS on the GT3?
Any idea what's the lowest pressure you can safely start on on cold tires?

Thanks[/QUOTE

I also drive to the track 90 minutes each way. Different story if you are trailering and have Hoosiers I would imagine.

 

Today's findings at buttonwillow.

Ok, I'm running a 2006 997S with Michellin Pilot Super Sports.

I'm only in the yellow group so faster driving may effect results.

First run was at 8:40 am for a 20 minute run.
Starting cold pressures were 32/36 psi.
At the end of that run I was seeing 38/42.
The ambient temp was cool so they weren't
Greasy so I left them alone.

Second run was at 10:10.
I was going faster this round and the amb temp was rising.
And things were starting to get greasy.
End of the session pressures were 40/45.
I bled of some pressure to bring them down to
36/40 (still hot)


Third run was at 11:45 and amb temps were in the low 80's.
Things got really greasy half way through the session
So I bled off some more getting them to 34/38 hot.
My tpms gave me warnings about having a flat tire with the display
Showing -7 on the rear display.

This pressure seemed to be pretty soft for the first lap but then they settled in
And never seemed to get to that greasy place even on subsequent runs
With ambient temp at 90 degrees and some much faster laps.

So I basically bled off 6psi from the fronts and 7psi throughout the day to get the tires to maintain grip. The outer edges put in some work but I'm running on a stock suspension with an alignment that's a slightly more aggressive setting than factory spec. Really only noticed understeer once and it was all my mistake and even then it was minor. The rear end was pretty planted.

Then I added some pressure back in after dinner to get back to the hotel.


Hope this helps.

Chris, you are in a 4S and faster than me so you might want to start off lower to begin with.