If you aren't maxing the weight rating of the tire, you don't usually want to be at max pressure. The wider the tire, the more sensitive they are to proper inflation.
If the centers of your tire are wearing faster than the edges, you need to lower your pressure. If the edges are wearing faster, raise the pressure. It might take quite some time to get a feel for what provides the best tire life.
To complicate things further, you can sacrifice tire life for either mileage or comfort, as you see fit. Running higher pressure (up to the max) will lower rolling resistance and increase fuel mileage. Probably won't be significant on a truck, but a car can see a big gain if you don't mind buying new tires sooner (IMO you spend more on tires than you save in fuel). Lowering pressure will increase comfort and traction, but wear the edges of the tires more. If you lower them too much, you can overheat the sidewalls and blow out a tire, which is dangerous.
For the stock tires, I would try running them down to maybe 40 in the rear, 45 in the front and see how it rides. I wouldn't go much lower than that on such a narrow tire. On my 315/70R17 I run ~30 rear (depending on how much traction I want) and 35 front. I'll pump the rear up to 40-45 if I am towing heavy (they are rated to 50 PSI).