I've searched a bit and cant get a solid answer. What is a good pressure to run a 315/70/17 10ply MT tire?? On a stock 17x7.5 wheel, mostly on road.

 

10 ply, never run under 45 psi then adjust from there for what you are carrying or pulling for load

 

Allllright. Thats that'll work for me. Maybe new pictures in the not-so-distant future.

 

If they are a max 80 psi, use 50 and do not go below 45. If they are a max 65, use 45 and do not go below 40.

 

Since you are using the narrow OEM wheels you will want to be at the low end of the recommended pressure for daily driving. This will help prevent the tread from "crowning" and the center of the tread wearing prematurely.

 

I agree with Wandell on this one,too. I ran 315/70/17's on stock 7.5" wide rims and this first set I had, I ran around 40 psi, and even after rotating, they wore in the center section the most. I clued in, once I had to replace a set of tires. The next set on the same rims, I researched the problem,on this forum, and adjusted my tire pressure down,to take out the crown in the tire that is formed when you put a wide tire on a narrow wheel. I used some chalk to color a spot on the tire, then drove a bit, and saw that my pressure was too high, and then aired down a bit, until the most tread was in contact. I ended up running at around 32 psi. I never had any issues with such a low pressure,on the highway,or around town.
I'm still running that set of tires, although they are ready to be replaced, and I bet I've got 70k on them.

 

Ok so now I got not below 40 and 32. haha. Well I'll have to do what you did sledman just see how it is. I'll ask to put it at 45 and go from there.

 

Just see how it goes for you. Pay attention to how it wears and adjust your pressures accordingly. It's not a "set and forget" type of thing, and everybody will give you a different number, as to what's best, but your set-up might be different.

 

It depend on the tire. As I stated, it depends on the max pressure. If it is 80psi, I would not go below 45. If it is a max of 65, I would not go below 40. Different tires with different load ranges and max pressures require different answers.
As for 32, that could be dangerous, if you do a lot of highway driving. Especially if it is a LR E with a max of 80. That 99 F150 is probably 500lbs lighter than your 05.