but when your tyre heats up. your tyre pressure goes up also! so you may start off at 25psi and finish at 32 hot. (example) I know some of you may know this
so it actually takes a few laps to get going to build the pressure and get to optimum.
now with that in mind and our level of ability. our sessions or races wont last longer then 30 mins. you have to balance out what you think is best. do you want to be relatively quick all session. or maybe push that bit harder at the start and mid session and lose a little time at the end when your tired. the car is tired etc etc etc (going at it for 30 mins is hard graft!!)
this wont work of course if your running rubber bands, IE 225/40 y18's
where the tyre will just fold over. what racing cars do you see running these tyres anyway??
the problem with going higher pressures is if you start at 40 psi. (tyre is rated max 45psi) and your tyre gets hot, pressure may well go past maximum. your really starting to take away from your grip levels.
it is a fine balance, and it differs for each driver let alone tyre brands, car set up etc.
My advice is to play with different pressures and keep an eye to see if your tyres are rolling (good tip with the chalk earlier in the thread) and see what works best for you!
make sure you write down the starting pressure (cold) because adjusting pressure when tyre is hot will leave you over inflating your tyres!
there are lots of books about all this so we are just scratching the surface here.