Hey everyone. I was looking at threads regarding tire pressure for the last hour and didn't get any answers for my question so I am hoping that someone can help. First, let me give you a little history on my tires.

Tire History...
I rotate my tires every 6,000 miles & get a wheel alignment at about the same mileage. (I have lifetime alignments with Firestone)

I have an 05' F150 FX4 that came with P255/70/17 tires. I ran my first set of General Ameritrac A/T's at 35.5 lbs pressure. They corners of these were pretty worn by the time I took them off. I got 42,000 miles out of them. Ok tires...

My second set of tires wore much better at 36 lbs. They were P265/70/17 Firestone Destination A/T's. The tires wore very even across the tire. I got 20,500 out of these. They had a lot of tread remaining, but the rubber wouldn't hold the road. The tires would spin starting out and slide on turns. Very dissapointing and scary for such a highly rated tire.

My current set of tires are the Cooper Discoverer ATR's in a LT265/70/17 "C" load rating. These tires corner and haul like champs, but ride a little tougher. I keep 44 lbs in the front and 40 in the rear. I do change the pressure in them when hauling or towing. Usually 48 in the front & rear. (max of 50 lbs) They are wearing great. The middles are wearing slightly faster than the outsides, but I prefer this for traction. My thoughts are that roadwater gets pushed through the treads from the middle of the tire to the outside, so it only makes sense to me for the tire to have slightly more tread on the outside of the tire to avoid hydroplaning. I have 26,000 on these now and should get around 40,000 miles on these tires. I am very satisfied with these!

I have a set of Goodyear Wrangler SilentArmor tires waiting to be put on. I am switching back to P-metric, because I don't haul like I used to anymore. I am bumping up my size to a P255/75/17. In english units that is going from a 31.7" to a 32.1" tire. And yes, I know they are about 1/2" inch narrower than my last two sets of 265's.

My truck's tire inflation sticker recommends 35 lbs of pressure in my OEM P255/70/17 tires. I am switching to a 1" taller tire than stock. (P255/75/17) Both tires are rated for a max of 44 psi. I know the new/taller tires have slightly more carrying capacity than the original P-metrics. My thought is that I should up my tire pressure to around 36.5 - 37 lbs to avoid the rounding of the tires and reduce sway and corner better. (especially with taller tires) Being that I keep my truck in a garage at about a temperature of 60 degrees and will be going outside this winter into 30 -40 degree cooler temperature, I should add another 2-3 psi per tire. That would take me up to about 38.5 psi per tire.

Question:
Is 38.5 lbs too much pressure for a P-rated tire to wear well with daily driving? I don't mind the middles wearing out slightly faster that the outsides, but I don't want to burn my tires off prematurely.

Any recommendations?

What tire pressure do you use with your P-Metric tires?

 

You get no better load carrying by going over 35 on a p series tire, unless it is an XL tire, which would have a max of 50. Anything over that is only for sidewall strength in things like towing.
As far as the LR C are the wear in the middle means they were over inflated, probably the front as you did not need more that 40. Wearing in the middle does not mean better traction, probably less as less tread will be on the road.