Tire Inflation Dilemma
I recently had a stem replaced on one of my real duallies due to a slow leak. When the guy inflated my tires he set the rears for 80PSI and the front for 65PSI. He said all Class Cs should have 80PS...
Forum Discussion
maillemaker wrote:I would trust the printing on the sidewall of the tire first.
This could be dangerous. As I said in my example, my rims that came with my RV are only rated for 65 PSI max. My tires can be inflated far beyond that and must be to achieve the full E rating. So I run at 60 PSI and am not getting the full rating.
Load rating D tires could have a load rating of 1,220 pounds at 65 PSI, Load rating E tires could have a load rating of 1,520 at 80 PSI.
I'm running Firestone Transforce HT LT215/85R16 tires that are load rated E at maximum PSI (80 PSI). But my rims are only good for 65. So the tires are de-rated when run at a lower PSI. AT 80 PSI, my tire has a load rating of 2,680 pounds.
Sadly it is hard to get the derating information from the manufacturer. So I just have to hope that at 65 PSI my E-rated tires perform at least at D rating.
Steve
Here's Firestone's charts for LT tires (and some other flavors as well). LT215/85R16 tires inflated to 65 psi are rated for 2335 lbs (single) or 2150 lbs (dual) per tire. It looks as though they rate the loading at a given pressure identically for all load ranges, with the difference being that the higher load ranges can safely be inflated to a higher pressure and so carry a larger load.
The tire inflation charts vary little if any between tire makers for the same size and type of tire. For practical purposes, this chart could be applied to any LT215/85R16 tire.
