On your RV, there should be a permanently mounted placard somewhere in the rig. It will have the various tire pressures recommended by the manufacturer to be used when the rig is new and empty.
By the time you add your groceries, water, liquid refreshments, etc., you have probably added hundreds of pounds, and it may not all be balanced.
The best way to know exactly what pressures to run is by having your vehicle professionally weighed. Once you know the weight of your RV, you can use your tire manufacturer’s load and inflation table chart.