Suggest - IMHO of course and there are other opinions around too
1. mark the tire with chalk on the roll over edge point (some tires have a mark on the tire for this purpose)
2. start with the pressure 5 PSI higher than street use (Car Manufacture's PSI)
3. after first several laps and temp is up, check chalk mark to see where the roll over point is located on the shoulder/tread interface
4. reduce the PSI until the rollover point is at the exact edge of the tread
This assures you are using all the tread for traction
Good luck,
Ed
Flame suit on!!