Originally Posted by MSHappyCampers
As F4Gary said, the only way to do it right is to take it to a local truck stop and have it weighed. It's best to weigh the four corners individually, but if the truck stop can't do that then just weigh the front and rear axles individually.
Once you have that info, go to the Bridgestone website and find the inflation charts for your tires. I always add 5 PSI to what the chart recommends!
Roger Marble, aka Tireman9, an IRV2 member and retired tire engineer recommends adding 10% psi. In addition, even if you weigh all four corners, all tires on an axle need to be inflated to the same psi, based on the heaviest corner. Here's the link to Roger's blog which has all the info you need and more:
In the meantime, assuming your tires are the same size and load range as those on the door sticker, just inflate to the pressures on your door sticker until you can get your rig weighed. The psi embossed on the tires themselves is the maximum for the tires and, although OK, is more than you need and will result in a hard ride.
Note that all pressures are "cold pressures" which means the tires should be at the ambient air temperature (not driven for two hours or so).