I pulled trailers to make a living for over 11 years. One thing I've found is the tire on a trailer last longer with max pressures. Watch a tire on a trailer as it slides sideways (side scrubbing) going around a cornor. The tire with max pressure will hold its shape better to protect its internal belts and protects against sidewall cuts and bruises from the rim while rolling over a curb or pothole/etc.
Goodyear says this:
Goodyear max tire pressures
Special Considerations
Unless trying to resolve poor ride quality problems with an RV trailer, it is recommended that trailer tires be inflated to the pressure indicated on the sidewall of the tire. Trailer tires experience significant lateral (side-to-side) loads due to vehicle sway from uneven roads or passing vehicles. Using the inflation pressure engraved on the sidewall will provide optimum load carrying capacity and minimize heat build-up.
Carlisle also says: (snip)
However; trailer weight does not fluctuate sig-nificantly with variances in fresh and waste water and supplies, and trailer owners should always inflate to the maximum pressure listed on the tire sidewall. The inflation figures are for cold tires; if you check pressure after the tire has been driven and thus warmed, you'll find it higher. This pressure rise is normal and accounted for in the maximum cold-pressure rat-ing.