[laverdur]

As was previously stated, tire manufacturers take normal operating conditions into account when designing a tire and specifying the max inflation pressure. Some sources say that for every 10 degrees in temperature variation, you will see a 1-2 psi change in tire pressure. Altitude also affects tire pressure to the tune of about 2-3 psi per 5,000 feet elevation change. Sun on the road and the color of the pavement will also effect tire pressure. On a bright sunny day, a white/gray concrete road will not absorb as much heat as a blacktop road. The tires will pick up some of that heat from the roadway. I carry an infrared thermometer and during rest stops I check road temperature and tire temperatures. I also hub temperatures and disc/drum temperatures. It only takes a couple minutes to check all 8 wheels. Tires on the sunny side of the rig will be warmer than those on the shady side. Proper tire inflation will ensure that the tire is running as cool as it can under the prevailing driving conditions. A cooler tire has less temperature rise. I have started towing days on a valley floor of 1,000 feet at 55 degrees. During the day I would experience temperatures up to 100 degrees and I would have elevation changes of up to 7,500 feet. My TPMS has never screamed at me for tires being over temperature or over pressure and I it set to be more sensitive than the default settings. I stick with 110 psi and I've had good luck for over 80,000 miles.