Originally Posted by cyccommute

Wrong law. Or, rather, too complicated. There is no change in volume on a set of tires so that drops out. The amount of air is constant so the number of moles drops out. The gas constant is the same independent of temperature and pressure so that drops out. All that is left is the relationship of pressure and temperature or Gay-Lussac’s Law. Another way to state it is P1/T1 = P2/T2. Solve for whichever variable you need. If you do the math (more like arithmetic), you’ll find that it takes a substantial change in temperature to have much of an effect on the pressure. Using 40 psi at 70°F, an increase in temperature to 100°F would result in 42 psi as the final pressure. Not enough of a change to be of any concern.

The concern for motor sports is probably overblown. For example, a change of 330°F (from 70°F to 400°F) results in a pressure increase of 25psi (from 40psi to 65psi). Not all that much of a change.

For bicycles, the rate of diffusion from the tire is high enough that being absolutely accurate and precise about the pressure measurement is meaningless. The act of measuring it is going to fall in to realm of the Heisenberg uncertainly principle. The pressure before the gauge is attached is going to be different from the pressure after the gauge is attached.