"To really set it right you need to weight the RV fully loaded and get axle weights. Then, look up your tires on the manufacturer's load inflation table and inflate to the pressure for that weight. "
Yep, using the sticker and blindly inflating to the max on the sidewall is a very bad idea. Also, how old are the tires? Check the DOT codes and if they are 5 years old or more plan on replacing them soon.
Good luck.
:C