Originally Posted by Burtim
So, the Michelin tires say 44 Lbs at full capacity. The door says 33 Lbs. What is the correct value...and should it be different when loaded (or towing) versus empty.
Check out tire.rack's tire tech pages.
The Michelin side wall probably indicates Max Inflation Pressure, unless yours is unique. You never want to go over that COLD.
The door jamb number is what the engineers at Jeep recommend for a decent combination of ride comfort and tire longevity under nominal load. There's a pretty good write up on page 379 of the owners manual, however, that is GENERAL information and may not apply to your driving situation, or even your tires.
A good tire shop will typically be more accurate if you regularly run your Jeep heavily loaded, as you typically want to add more pressure. The owner's manual statement about 75 mph on snow tires must be written by someone not familiar with today's premium snows... e.g. those which set an ice speed record in excess of 200 mph.
If you drive a lot on freeways, you can usually get a bit better handling and response by going up just few pounds, without risking excess wear--presuming the tires are good enough to handle it.
I usually run 36-38 lbs on the Michelin Latitudes, and about the same on Nokian Hakka 7 studs, taking a possible very small penalty in ride quality for better driving feel.