Sorry Andy but that's not correct.
The value to which you refer is Max Pressure. This is a value that is required to be given to meet USA requirements. It is not a guide to the inflation pressure for any vehicle. The pressure is determined by the axle loading as determined on a weighbridge and reference thereafter to the tyre manufacturer or as calculated by Tyresafe:
Our motorhome tyre pressure calculator gives you the correct pressures for your motorhome. Check your tyres regularly for your safety.
www.tyresafe.org
Or the website here:
The correct inflation pressures for your motorhome's tyres are extremely important. Here is some information to help with your motorhome tyre pressure
www.tyresafe.org