997s , with 19" ,spec tire pressuer for street is 37F/44Back , using R888's at DE would 30 F/ 38 Back be good target for cold start.

 

difficult to understand your question, i would aim for 34f/38r hot. so cold it should be 30/34 or so - start from that and keep checking it.

 

Stock street tires cold pressure is 33/39. I suggest using that for your first 3-4 DE's. Street tires sidwall is not as firm as a r-comp tire like a R888 Toyo. If you run less pressure and use stock alignment you will not have enough negitive camber and the tire rolls over. So for learning and starting out just use the stock cold pressure.

For Toyo R888 and you have the proper alignment done I have found as well as other that a hot pressure max of 36f and 37 rear works very good...nothing over 38. If you are experienced at the track and are running at the top of your group and at least 8/10ths then in the summer you will probably heat up the tires around 10psi. So for the 1st warm up session I'd start out R888's on a 997 car at around 29 or 30 and bleed air from there.

 

I heard form a driving instructor that with newer wheels, 19 inch and larger, there is no real need to mess with the pressure too much since the main concern in the past was keeping the walls of the tires parallel to track. With low profile tires the risk of wall bend/collapse is minimal, just what I heard.

anil

 

guys sorry for changing the subject, but wouldn't using nitrogen for the tires be better at the track since its more stable( psi) than air ?

 

You will have less change in the pressure but if you get hot and it goes up and you bleed some out you will not have access to fill with nitrogen at the track. You then end up mixing.

 

You still have to worry. Proper camber is important for good tire wear.