Generally you should not adjust pressures for either temperature or altitude unless you expect to stay in that area for some time. Now how much is "some"? Most alleged experts give answers like "several days" or "a couple weeks". The gist is that you do not need to adjust the tire pressure every morning, just because you drove a couple hundred miles to a slightly different climate, but you should adjust if the change is long term.

Probably the key thing to remember is, if you do make an adjustment, be sure to adjust back when you leave the area.

In case someone is interested.
The formula for pressure increase in a constant volume container (tires are pretty close to a constant volume)is:

P1/T1= P2/T2

Where P1 is the initial pressure, T1 is the initial temperature.
Where P2 is the new pressure, T2 is the new temperature.
The temp must be in degrees kelvin.

Or P2 = P1 X T2/T1

For P1 = 85 psi, T1 = 294.26' kelvin, and T2 = 305.37' kelvin. (T1 = 70'F, T2 = 90'F)

P2 = 85 X 305.37/294.26 P2 = 85 X 1.038 = 88.21

So for a 20' F increase in temp the pressure should increase by about 3 psi.

Way impressive formula. Way more work than I care to do. I appreciate your taking the time to let us know. But . . .

How about you just create a tiny little program that will let those who care to calculate the expected pressure change when taveling through different climates.

For me, I just don't care so long as my pressures don't drop below the minimum for my axle weights.

That's probably why I bought a Preseeure Pro last year.

I wrote an Excel spreadsheet that does the calculation. If anyone wants it I can send it to their email address. Just let me know.