WARNING: The following procedures are USTMA recommendations for MH tires and cannot be used for the inflation of RV Trailer tires. Those inflation pressures are determined by a completely different FMVSS standard.
Determining Proper Inflation Pressures; Use of the tires, wheels, and inflation pressures as specified on the vehicle tire placard, certification label or in the service manual ensures that these components can carry the maximum rated axle loads (GAWR) and maximum vehicle weight (GVWR), and also maintains other performance characteristics, if any, intended by the vehicle manufacturer. At a minimum, the tires on each axle should not be overloaded or under inflated if the vehicle is properly loaded.
With actual weights of the loaded RV acquired by weighing, it is possible to compare them against the GAWR, GVWR, and tire capacities posted on the vehicle tire placard or certification label.
These actual weights are also what should be used to determine any increase in inflation pressure for the tires, if required. Inflation pressure recommendations may also be determined based on the tire manufacturer’s specifications, which define the amount of inflation pressure necessary to carry a given load. These inflation pressures may differ from those found on the vehicle tire placard or certification label.
However, never use inflation pressures lower than specified by the vehicle tire placard, certification label or owner’s manual. Nor should inflation pressure exceed the maximum pressure molded on the tire sidewall.