it depends. when I road race...I mean DE events at the track, tire pressures can go up 5-10psi once the tires are warm when you're having fun (~weather). So you adjust cold pressure accordingly to meet the target. Works the same way for motos and karts, etc. My bro-in-law races pro-stocks and they run them almost flat it seems...only a few psi. So, for street use find the best handling cold pressure for your tires for your car and weather/temps. It may not be the same as what is printed on your door or on the tire. I tried nitrogen at the track and it made them more stable, but still increased pressure with heat. Not worth the trouble IMHO... until my compressor can filter out the air we breathe to produce nitrogen.