I adjust rear tire pressure depending on what I'm doing. When I am hauling materials (landscape 6x8 ties, stone, etc) I put the rears up to full pressure, which I believe is 75psi. I confirm it with the door sticker. My trucks's tires can go up to 80psi. Fronts I keep at 65psi.
When I know I'm just going to be running errands and/or not hauling for awhile, I'll put the rears down to 65psi. Lower pressure with an empty bed really improves the ride.
My truck rides best when loaded near max - then it has a surprisingly comfortable suspension.
F150 1/2 ton type trucks don't usually have that large of a weight carrying spread, so no need to go through adjusting the tire pressures.