Thor Forums

[lwmcguire]

Originally Posted by Oneilkeys

No. The Psi tire pressure embossed on the side of the tire is the maximum cold psi that the tire is designed to hold, whether it is under any load or not. That tire and that pressure determines what safe load the tire can carry. Most tires are not (and don’t need to be) filled to max pressure. The psi in the tire will increase as the ambient air temperature increases or as you run your tires and heat them up. The front tires in my RV should be run at 80 psi or max pressure for my Michelin tires to carry the 4000lbs of weight load on the two front tires. When I travel south in the late fall, I fill those tires to 80 psi at about 50 degrees F. As I travel south and the ambient air temp increases to 60 and 70, I have to let air out of the tires in the morning to keep them below 80 psi because the psi increases with the ambient temp. When I run my tires at 70 mph on a hot road, my Tire Minders will tell me that the temp in my tires has increased from the ambient temperature to 90-100 degrees and the psi will rise 5 lbs or more. That is what the tire is designed for.

Well you are partially right in that is the starting point when airing up the tire

The stamped pressure is actually the minimum for the maximum load because of what you brought up (I did not state anywhere to inflate above the sidewall psig)

If you are driving and the tires heat up as they do and the pressure increased accordingly then you are now operating your tires lets say with 90 psig which isn't now the minimum pressure but is the new pressure due to the increase from the tire operation flexing from the load and the ambient temperature

In other words you don't stop and let the pressure back down to 80 as the tires heated up and increased the pressure, you keep on driving. That

Setting the pressure cold is correct based on the maximum tire load