I just upgraded my OEM D-load tires to Maxxis E-load tires (same size). When I removed the original tires I found there is no indication anywhere on the wheels of what the max pressure is. They do have a stamp showing a max weight of 2,830. The OEM (Lionshead) tires were 65 psi so I wanted to be sure the wheels could handle the increased pressure of 80 psi.
I sent a message to Lionshead and got this response the next morning:
Lionshead shows the max weight rating for all of their wheels on their website. Most FR trailers are equipped with Lionshead wheels so you can cross reference the weight spec to determine the max pressure.
Oh, went ahead and installed the new tires and pumped to 80 psi.