[Brentwe]

If you are wanting pressures for tires on an unloaded vehicle, go to the tire manufacturers inflation load chart, as noted, vehicle recommended pressure is for gvw of the vehicle. Max pressure on tire is for tires max rated load, may or ,may not be same as vehicle.
3500 Ram truck 80 psi when I'm hauling, rears are at 45 once the rv is parked for winter, that is more than enough pressure to carry an empty truck box.
Hope this helps.