Tire pressure in trailers....

[Mr. Sandman]

Now I am really confused.

I think the only sensible reading to put on the sidewall is the cold rating . No one is going to weigh each axle and adjust tire pressure as a function of temp and weight, that is absurd.
One has to assume there is a significant safety factor on over-pressure on this reading and that the over pressure that is created by heat will be within that margin.

I have an uncle that invented the run-flat tire (sold the patent to a giant tire manfuc) The testing for this tire was like 12 years. (Believe it or not it stemmed from research used to develop the wheels on the lunar rover that drove on the moon) We use to joke that he was "re-inventing the wheel" (an engineering joke) I will ask him, maybe he knows what the safety factors are, I would bet they are at least 2X the sidewall rating.

[wrench]

This is from my Atlantic Trailer Manual.

Maximum Inflation Pressure

A tire's maximum inflation pressure is the highest "cold" inflation pressure that the tire is designed to contain. However the tire's maximum inflation pressure should only be used when called for on the vehicle's tire placard or in the vehicle's owners manual. It is also important to remember that the vehicle's recommended tire inflation pressure is always to be measured and set when the tire is "cold." Cold conditions are defined as early in the morning before the day's ambient temperature, sun's radiant heat or the heat generated while driving have caused the tire pressure to temporarily increase.

For the reasons indicated above, It is also normal to experience "hot" tire pressures that are up to 5 to 6 psi above the tire's recommended "cold" pressure during the day if the vehicle is parked in the sun or has been extensively driven. Therefore, if the vehicle's recommended "cold" inflation pressures correspond with the tire's maximum inflation pressure, it will often appear that too much tire pressure is present. However, this extra "hot" tire pressure is temporary and should NOT be bled off to return the tire pressure to within the maximum inflation pressure value branded on the tire. If the "cold" tire pressure was correctly set initially, the temporary "hot" tire pressure will have returned to the tire's maximum inflation pressure when next measured in "cold" conditions.