I've had it with cheap Chinese trailer tires!

As with vehicle tires you should run trailer tires depending on weight. For example, on 225/75r15 10 ply trailer tires, the max psi is 80psi per the load rating. However i would keep 60 psi in them for pulling empty and light loads. Then bump em up for heavy loads. Technically your suppose to adjust air pressure according to load. Running trailers empty at max psi is just going to wear the center of the tire.