The ideal pressure varies based on several different things. Driving style, typical loads, and the type of tire. The chalk test and some experimenting to see how the ride and handling are affected at different pressures are the best way to do it. I will say that you typically can get a better ride, better traction, and better tread wear from the optimal tire pressure, and on an empty truck that is typically lower values.
I haven't bothered to mess with the pressures on my PW that I just bought last month mainly because I have a set of 35's to go it next week, but on my last truck (Chevy 2500HD crew) running larger than stock tires with a max psi rating of 65 I found that about 50 psi front and 40 psi rear was a good combination for normal driving. The front tires have more weight on them plus more lateral strain from turning then the backs and why I went higher. Back tires have a good amount less weight on an empty truck, plus lower pressures helps the traction and ride especially on the back since the spring rates are designed to handle some sort of load. I ran two sets of the same tires on this truck and got very even wear and had a noticable difference in ride quality and traction as compared to running at max pressure. Never adjusted the front pressure, but would bump the rears up to the max 65 psi when towing heavy loads (near the max tow rating) for long distances on the freeway. If only towing for a short distance on back roads, or a smaller trailer, I didn't bother adjusting them.