New LT tires on f150, what PSI

lcirelli wrote:
Hi, just bought new tires for my 2011 F150 max tow, had the p285/65 r80 and upgraded to the Michelin LTX M/S2 E rated tire same size. I used to run the p tires at 35 unloaded and 45 towing. When I checked the PSI after they installed the tires, they put in the same 35 as was on the door sticker. when I called Ford they said the same as the tire dealer, when I called Michelin, they said the same thing. Am I crazy, but shouldn't these tires be put at a much higher PSI. My trailer has a very heavy tongue weight. My rear axle came in weighing 3700lbs with my WDH on. What PSI should I put the tires at towing and not towing? I have read so many different forum answers, it seems no one has a good answer. When I called Ford I asked what PSI do they run on the F 150's that had the LT tires as standard equipment, and he couldn't answer me. If someone has an F150 that came standard with the LT tires, what does it say on your door sticker? I don't want to ruin these expensive new tires by running them too low.

This is some information in this post that doesn't seem right:

1) The tire size. Tire Guides doesn't have a listing for a 2011 Ford F-150 that says the original tire size was P285/65R18. I also don't see Michelin listing that size in an LT for the LTX M/S2 (or in a P) I do see F-150's with a P275/65R18, and Michelin lists a LR E with that dimensions.

Ford also lists that LT size as needing 40 psi. However, my background say that an LT tire needs to have 15 psi more to carry the same load as a P type tire with the same dimensions.

So if my info on the tire size is correct, I would go with what Ford says for the LT's - even though their hotline folks didn't seem to know about that. I'm guessing the person at Ford is driven by VIN number and did not know how to look it up any other way.