WrightOn,
Know what the load is on your tires. Use the weight/inflation chart and add 5psi to the recommended pressure.
ORRRR simply, blindly go with MAX sidewall cold inflation.
MOST RV's need MAX as that is what they determine the carrying capacity by is the tires.
Some RV's like DRV for example have triple axles and they also have GY "H" tires that have MAX listed at 125psi. That condition the tires can be SAFELY ran at much lower pressures.
Bonus of using the charts and adding 5psi is better stopping, ride and tire wear. straight from the mouth of GY Tech Support.