Tire Pressure Calculator

A tire is a sealed volume of air, so its pressure moves with the temperature and with the air pressure outside it. Enter the pressure you set and the two temperatures, and this returns what a gauge will read now, worked through absolute pressure and absolute temperature rather than the rough psi-per-ten-degrees shorthand. A second mode does the altitude version, where the air inside is unchanged but the air outside has thinned, using the standard atmosphere. It does not recommend a pressure for your car: that number is on the placard in the driver's door opening, and no formula can derive it from a load or a tire size.