Originally Posted by Barbieri
I would leave the tp alone. After driving a while the tp will be over 70. The ambient air temp determines the tire pressure. If you do that would be spending all day adjusting you tire pressure. By the way what is the ambient air temp?
1. Assuming your tires are ST type Load Range E they most likely show 80 psi molded on the tire sidewall. To get the lower Interply Shear I suggest you use 80 psi as your "C
is the pressure when tires are not warmed by either driving or in sunshine for at least 2 hours.
" air temperature is nominally the air temperature in the shade
4. Yes tire pressure will increase when you drive on the tire. The normal change is about 2% for each change of 10°F. I have covered this in detail with the math formula in my blog. Tires are designed for this pressure change. It could even be argued that tires are depending on this pressure increase do deliver longer term durability as ALL tire development testing and ALL regulatory testing is done with air and the inflation pressure on the drum tests is allowed to increase accordingly.
5. You do not need to adjust your tp during your travel day. The intent is to start each day with the correct CIP
6. If you run a TPMS, which I strongly recommend, you will see your tp go up and down during the day. This is normal and should be of no concern unless you see a drop below your CIP
. I set my TPMS warning level at 5 psi below the CIP
Go to my homepage if you want to learn more about proper care loading and inflation from a tire design engineer.