Originally Posted by travelingjw
In all the reading that I've done of the forum, the one subject that is still not clear to me, do you stop during the day to adjust tire pressure? For example, we stayed at Grand Canyon, checked tire pressure prior to leaving, temperature was 34 degrees and of course we were at a high altitude. In that day we drove down the mountain, crossed into Arizona, hit the Nevada desert, etc. Obviously the outside temperature and the altitude affected tire pressure. What is the right thing to do? Is there a guide somewhere that discusses when it is prudent to stop, how long to let tires cool, etc. We’ve owned our TT for 2 years, driven over 8,000 miles, and tires show virtually no wear.
The tire industry says to check your tires "cold" That means when they have not been warmed up by driving or being direct sun for previous 2 to 3 hour. In other words the temperature in the shade.
I cover this and related items in the RV tire blog.
Basically check and set in the AM befopre you travel. Your TPMS will show temperature and pressure changes during the day depending on speed, load and if one side of the RV is mostly in the sun or not.
Pressure will change by about 2% for each 10F. Temperature will normally go up by 10 to 50 F depending on speed and load.
In my Class-C with a 15% Reserve Load and running +10 to +15 psi over the minimum needed to support the measured load I see about +10 to +15F over Ambient. I also see + 5 to 10 psi.
In the evening I shut off the TPMS. In the AM when I get up I turn on the TPMS and get mycoffee. A few minutes later I can run through all the readings. Unless there is some significant change (more than +/- 5 psi) I don't need to adjust anything.
Trailers normally should have tire pressure set at the tire sidewall pressure when "cold". Hopefully your measured loads are only 85% of the tire max load capacity.