Tire pressure and altitude

Good article. My particular situation involves tire pressure monitors sealed to the valve stem so I don’t know if the article specifically applies. And I experienced the reverse. At high altitude my pressures registered surprisingly low. Maybe I measured my tires before the trip at a higher ambient temperature than I remembered. I always, though, do check completely cold, without being driven at all. I know in the mountains I was at 50 degrees when the tires read around 100 to 102. Quite a drop. But the change in temperature from home to the mountain morning may have been as much as 45 degrees I guess. I will check tire pressure now that I’m back home and compare. I have had too many blowouts in the early days of my RV career due to improper pressure (I now have a monitor and check pressure diligently) to casually ignore such low pressure readings. Plus, I’ve always heard that you should never “air down” due to higher pressures after driving. But it still seems to me that had I refilled the tires at altitude to 110, like I always do before a trip, I would have over inflated them. Doesn’t that seem right?

Temp/operating heat...altitude has little to do with pressure loss 80-110 psi.
WE sometimes stay at 8800 feet in the San Juans where morning temp around 30 degrees and upper 70s day time. Drop back to 1500 feet where we live and pressures are at max cold set morning temp.

Good article. On trips across AZ or CA desert in the summer I air down 5-7 lbs in the mornings when the temps are 70-80 knowing that by noon they will be 110+. Plus, my route is at a lower elevation than my home so I will be 2-3 lbs over just due to altitude changes by the end of the first 200 miles.

Both, here is a good article: Tire Pressure