tyre pressure for track use

[adevictoria]

yesterday i was tracking at montmelo track (barcelona) and think i had too much pressure in my tyres. i started with 2.7bar at rear and 2.3 in front but after 15 minutes they were allready very high. witch would be the "good" pressure to start with? would it be good idea to stop to take some air out when it gets to certain pressure?

car is 997s and tyres contis (not good at all to my opinion)

breaks were really great with no signs of getting tired. thats really a great thing use to my bmw.

thanks

[nick49]

I'm not sure about cars, but with motorcycle roadracing we would look for a 10% rise in pressure between cold and hot. If we got more our starting pressure was too low, less meant we were starting too high. After this we would go by feel as to how it felt handling wise and during braking.

[KevinC]

You should focus on your hot pressures. I think something like 2.7 BAR (rear) and 2.5 BAR (front) would be a good goal when you come in from a session on the track. Figure that your pressure will increase on the track by 0.3 to 0.4 BAR to set your starting pressure at the beginning of the day. After that, just use the hot pressure to make adjustments and ignore the cold/warm pressure before you start a session. At the end of the day, let the car cool down, then set the pressures a little above your normal cold street pressures.

It sounds like you started out too high.

Cheers,

Kevin