IMO, one should always consider the tread wear patterns when determining the correct tire pressure.
If the tread is wearing mostly in the center, reduce the pressure.
If the tread is wearing mostly on the edges, increase the pressure.
If the tread is wearing evenly, the pressure is just right.
What is important is the "contact patch", the size of the patch where the rubber meets the road. That patch should always be as large as possible, to ensure safety. That can only be achieved with the correct tire pressure for the existing load!
Tire pressures shown on the door jamb sticker (at least the ones I have seen) show the pressures needed for maximum GVW or GAW. If the rig isn't loaded that heavy, you do not need that pressure!
