I'd suggest you do some more researching. The BAL website (maker of the gadget) shows about 4 models, all of which only discuss mounting under trailers. A thread on the Forest River site discusses the mounts, one mentions it having a 100 lb capacity. Could be that this works fine for trailer-size wheels but might have a problem with our 22.5" heavy boys. You might want to contact the manufacturer directly with some questions before you dive in based on an Ebay listing (which also appears to be overpriced.)
BAL web site