Determine the proper air pressure the right way, by weighing your rig. Per Goodyear Because RVs can be loaded with many different configurations, the load on each tire will vary.
For this reason, actual air pressure required should be determined based on the actual load on each individual tire.
Inflation pressure should be adjusted to handle the tire carrying the heaviest load, and all tires on the axle should
be adjusted to this pressure.
Here it is
straight from Goodyear. Check the tire inflation charts. The pressure specified is to get the maximum traction and tread to pavement contact for the weight on the tire. Too much pressure and you get more contact on the inner treads. Too little pressure and you get more contact on the outer treads. Both lead to uneven wear.