[CALinSC]

My posts are not intended to contradict: they are from a vast reference collection of the way things are supposed to be done in accordance with the governing body and that body's accepted standards from such organizations as the TRA and USTMA.

Here is a take on the vehicle manufacturers recommended cold inflation pressures for OE tires. (OE tire load capacity and recommended cold inflation pressures for the replacements for replacement tires is derived from what the OE tires provided).

All reputable tire wholesale and retail dealers of tires will train their installers in the SOPs provided as industry standards by the USTMA.

The vehicle manufacturers recommended cold inflation pressures for OE tires are the minimum acceptable pressures for that fitment. That is supported by NHTSA with a short statement; “the cold tire inflation pressures depicted on the vehicle certification label are the correct inflation pressures.”

Determining Proper Inflation Pressure (USTMA)

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) - trailer axles - and maximum vehicle weight (GVWR), - self propelled RV - and also maintains other performance characteristics, if any, intended by the vehicle manufacturer. At a minimum, the tires on each axle should not be over loaded 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.