Tire Pressure

[travelite]

Ahh, Tires, one of my favorite topics.

Your tire's gauge air pressure (as measured with a tire pressure gauge) will increase approximately 2% for every 10 deg F increase in tire temperature. As an example: if you check your tire pressure when the ambient (and the tire) is at 75 deg F and the pressure is 100 psi, then if the tire heats up to 135 deg F the tire's air pressure will rise to approximately 112 psi.

Also, your tires gauge air pressure will increase as you ascend above sea level by approximately 0.5 psi for every 1000 feet of altitude. As an example, if you leave NJ with 100 psi and make a climb to Aspen Co, you'll ascend approximately 8000 feet and your tire pressure will increase to 104 psi.

The dynamic changes in air pressures are well understood by tire engineers. Turns out that a tire's stiffness (spring rate: lb/in) and dampening (lb-s/ft) both decrease with speed and are offset, to a degree, by increases in air pressure due to increases in temperature.