The door sticker is for stock tires, the ones that came with your truck and will work if you keep the same load rated tires on your truck. If you with a bigger tires, low profile or change load rating you can throw that door sticker out. Its meaningless.

By far this is the best advice I have heard on finding out your proper tire psi.
Smear baby powder all over the tread, drive forward 3 feet and stop, get out and look at hte tread patern on the concrete/asphalt. If you have pattern all the way across your good. If the center is weak your underinflated. If the sides are weak your over inflated. I have seen some recommendations to try and slide a credit card under the side lugs, and a host of over things.

More psi will give you a firmer ride, less psi will give you a softer ride. Firmer tires also give you a better sense while cornering, softer tires make it feel like your sliding around in the turns.
I run my BFG A/T at 42psi. Why? Because that is what I like. No scientific logic to it. They wear great and have great pattern for me. I don't mind the firmer ride.

Edited to add this. When I go 4wheeling I drop my psi down to 15-20.

 

good info......I always kept mine at 35, only because thats what it said on the side wall.

so a few pounds lower will give you better traction on snow/ice?

 

i dunno about ice but ondirt and mud, lower pressure will give you (somewhat) better traction.like a balloon, if you inflate it just a little, its muchharder to pop than if its overinflated. they are able to conform to the ground a little better than if they are super stiff.

from my understanding, thats why some people use beadlock wheels.beadlocks keep the wheels connected to the tiresin very low pressure siuations