Quote History Quoted:
Heat will cause pressure to increase, but heavier loads do not, it simply displaces the air into a small volume vessel. If you park your truck in the driveway and do not move it, but add a thousand pounds of ballast you have not increased the overall pressure of the tire, you have simply displaced into a smaller area.
Air expands with heat and contracts with cold.
30 PSI is 30 PSI no matter what happens, 30 PSI can be squeezed into a small vessel, which is exactly what happens when you put a load on a truck and that depends on how much side deflection your particular tire has, but is still has 30 PSI in that tire.
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Wrong. You displaced it into a larger area, by expanding the tire where it is not in contact with an incompressible surface, IE the pavement, road surface. When you squeeze a balloon, it does not get smaller, unless you squeeze it from every direction equally; it gets larger. This thins the walls unequally. You most certainly can pop a tire by overloading it at rest, unless something else fails first. Because the pressure is maintained by expanding the container, that is, the tire.
The tire pressure recommended accounts for heat increase within the designed load rating. That is why it is specified as a cold pressure.
The general rule is 1 psi per ten deg F up or down.