Tire Pressure Question

becker wrote:
This question has probably been asked before but upon searching I couldn't find anything.

When traveling from a northern state where the temperature is well below freezing to an southern state where the temperature is 70 degrees, how do you handle your tire pressure settings?...... and if the situation is reversed. When in a warm area and your tire pressure is set correctly (in the morning before getting on the road) and the next morning (in the cold area) your tires are showing 10 degrees or so low, do you take your tire pressures back to the correct settings before getting back on the road? Tire size is 295/80R/22.5 Michelins with about 2000 miles on them.

Where can I find some information of this subject?

Thanks.

First, you will find statements that there is a 1 psi change in pressure for every 10°F change in temperature - except that this is only true for passenger car tires. For truck tires and trailer tires, it's a bit more complicated: 3% for every 10°F.

Then it is a matter of how to deal with the situation you described: One day your in zero degree weather and then next you are in 70°F weather. Here's what I do:

Estimate the difference between where you are and where you will be the next time you plan to adjust pressures and go for the max. That is, if your situation is as described above (0° to 70°), then inflate the tires according to the current condition and forget about it until it is time to readjust. Yes, your tires will be over inflated, but not only are tires designed to withstand much, much more pressure than the maximum indicated, but also, the wear isn't as affected by the overinflation as much as you may think. Besides, one day's worth of driving is that big a deal compared to thousands of miles of driving.

The alternative is to constantly adjust the pressures as the ambient temperature changes. That's a lot of work and requires a lot of math.

Oh, and one last thing: It has been known for tire valves to freeze open, letting out all the air. So don't check your pressures when it is below 40°F.

And be sure to anticipate when it will be dropping below 40°F and set your pressures accordingly.