Tire air pressures checks

I got into a discussion recently with several fleet managers.

One of the topics we got into was tire air pressure.

Everyone one was in agreement that maintaining proper tire inflation pressure can save tire maintenance costs, improve fuel economy and lengthen tire life.

There was also a consensus about when the best time to check a tire’s air pressure.

That would be when the tires are cold - when the they have not been running for at least 3 hours. This gives a better reading than if you check the pressure shortly after driving, the managers concurred.

Tires flex when under load. This produces heat, and heat causes air to expand.

The fleet managers also were of one mind that the ambient temperature affects tire pressure. For example, if a truck was baking in the afternoon sun, the tires bathed in sunshine will have higher air pressure readings than the ones in shade.

The area that caused the most conversation was whether tire air pressure readings were affected by the position of a vehicle.

Would the air pressure on a truck parked on a very steep grade be different if that same truck were parked on a level surface.

What do you think the answer is?