Quote:
Originally Posted by RidingOnRailz
Semi-related to this thread:
What is the actual change in air pressure per 10deg F temperature delta -
1.0psi, or 0.8? I've read estimates of tire pressure loss/gain from half-PSI up to two-PSI on this objective internet we use!
Which one is iiiiiit??
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First, this deals with the Ideal Gas Law - which references absolute zero temperature and absolute pressure. So the answer depends on how hot you start and what elevation you are at. You'll get a different answer if you start at 30°F than 100°F as well as a difference at sea level or at 10,000 feet.
It also depends on the starting inflation pressure. You'll get a different answer if you are starting with 30 psi than if you start with 100 psi.
Having said that, if you have a 30 psi tire at 70°F at sea level, and the temperature rises to 80°F, the increase in pressure is 0.84 psi.
On the other hand if you start out with 65 psi (like on some LT tires), the pressure increases 1.50 psi.
I've worked with other tire engineers and have worked out a "Rule of Thumb" - 2% for every 10°F. It's close enough and easy to remember!