I run in hot weather (Middle east, Bahrain GP and Losail GP track), 27 front and 24-25 rear cold. I fluctuate from 26-28 front, and 22-25 rear cold, which gives me a 31psi front and 28 psi rear.
I find that when the front is less than 31/30 psi I get a squidgy feeling on turn in, just before I reach full lean, sometimes the bike leans to almost full lean angle, and then drops suddenly again, its like the bike is leaned over, but the contact patch is not on the edge of the tire, (as the carcass is too flexible), then the contact patch slips and shifts.....
I cure this with a bit more pressure in the front, 32psi when hot.
The rear works well with 28psi hot, any more and i loose traction.
The ideal pressure depends on the track temps and how abrasive the track is.
Also a little bit on personal feel, ie do you like a squidgy turn in with more grip, or a sharper turn in while sarafising grip.
Tire temps/pressures should be taken always when the tires are hot, ie off the track or at least off the warmers, tire pressure when tires are cold is very vague, and will vary alot depending on the track temperature.
Baseline: COLD: front: 29........rear: 25
HOT: front: 32 .......rear: 27
My routine: check psi before putting on warmers....check again after 35-40 mns
on warmers, check again right after 1st session.
Check again 'round 11 am when track is warmer...
Some excellent info here ---> http://www.diabloracer.com/phpBB3/index.php