daydark

Greetings! First of all let me apologize if this is posted in the wrong forum. Moderators feel free to move it.

I own a 2006 997 Carrera S with GT3 wheels and NT01 tires 305/30/19 in the rear and 235/35/19 in the front. When the tires were installed, Discount Tire inflated them (cold) to their stated specification 38/40, and the TPMS sensors were happy.

When I took it to the track, after a few laps the car felt like it was on ice, and I checked the tire temperatures and they were over 50 in both the front and rear! I reduced the temperatures down to 40/40 front and rear, but somehow I still feel this is too high.

I am looking for recommendations for HOT tire temperatures at the track. I'm astonished that they increased in pressure by that much from cold to hot! So what zone should my hot pressures be in?

Just as an interesting tidbit, by lowering my temps from ~53 to 40, I gained THREE POINT SIX seconds on my lap time, so it's obvious to me that tire pressures play a huge role in adhesion and grip. Any advice from members with more experience than me would be greatly appreciated!

NOTE: When I lowered the pressures by that much, I got the "flat tyre" indicator on my dash, which I knew was not correct.

Petza914

You need a larger front / rear pressure differential due to the weight of the engine in the rear. Setting the front at the same pressure as the rear will cause the car to understeer or push. For street driving on my wife's C2S with GT3 wheels I used to run 35 F / 40 R but have noticed the center of the rears wearing more than the sides, so have lowered both and am running 33 F / 38 R cold now.

BF951

I also have 06 C2S and have run various R-Comp like you have. They have varied slightly and alignment plays a role but I've achieved optimal grip and tire temps across the surface of each tire when they are in the 34-36 range HOT. I'll sometimes visit pit-lane 2/3 into a session to check true hot temps. Depending on ambient temps I'll start the session 26-30 cold before going out. 45 deg in April at 8 am in Watkins Glen is a lot different than 3 PM at NJMP in July. Ask other guys with similar cars and tires in your paddock.
Good luck!

tarmacrdr

I agree with the above comment. It is not unusual to see 10-12 psi different between cold/hot. I take them down to 25/28, and get the best grip/wear.

nwGTS

Cloudspin

My experience running NT01s (245/305) on '09 C2S and '12 GTS at Sebring for the past 4 years and 15 - 20 days per year is 33psi hot front and rear is optimal. I go out at 25 all round and then bleed as required if any get to 35 or above. Easy on the first few laps each morning until pressure comes up a little. Both cars have been driven at Sebring by pros Mike Levitas (TPC/DSC), Jim Price and Chris Hall. None reported any negative handling characteristics. I have two sets of wheels with NT01s. One is kept by a track services vendor (XP Motorsports) that comes to all of the Chin Sebring events. That set never sees any thing but nitrogen. I keep the other set at home and drive on them to HMS and PBIR events. That set sees only compressed air. There is a dramatic difference between the on track pressure increases between the two sets and much more coming in mid - session to bleed them down. These are just my experiences, but they are based on a lot of track days. Hope some of it is useful to you.

GT3_ISH

I run 34F and 36R. My car rides pretty stiff anyways so I'm used to the extra air.

ColoradoMark

I liked 32 all around hot, but next time I go I'm going to play around with dropping them lower a pound at a time.

cosm3os

I bought a set from Tom @ TPC. He recommended 32-34 hot.

daydark

Thank you for all the informed replies! I knew I'd get good feedback by posting here. It sounds like my assumption that 40 HOT was still too high. I guess I just got worried by the "flat tyre" message on my dash. Next time Out, I'll try pressures in the mid-30's and hopefully gain some more laptime!

Tom@TPC Racing

I go with 32-35 hot on NT01.
38 hot on Hoosier R7.