Isn't it amazing what we Airstreamers as well as other people do?
Like running pressures different from recommended.
Tire companies, especially the big ones, spend much time and effort producing tires, and then testing them for the tires optimum performance. They then publish these figures, and normally, the pressures go up as the weight does. However, remember that the sidewall gives a MAX pressure for MAX weight carrying capabilities. To get the best performance from our tires, we need to know the trailer weight and pressurize accordingly.
Then some guy installing hitches, or we, on a whim think we know better than do the engineers and their test results, decide we will run something different! The benefits of increased MPG (if it actually does increase it) are offset by earlier tire replacements due to worn center treads. Higher PSI also reduces the contact patch, traction capabilities (don't forget traction is needed for lateral stability as well as braking effectiveness) and ride softness (defined as stress on the trailer and its structural components). Tires have polymers and UV inhibitors added to the compounds to protect the tires, and they need flexing as well as heat to migrate through the tires. Yes, the least rolling resistance would be a steel-hard donut, but all the other qualities and performance needs our tires provide would be totally nill. Just my thoughts.
and on and on the debate goes...........