All of the major brands of tires recommend 8.25 wheels for 11R22.5 tires. Newer wheels have maximum weight stamped on them. The weight limit of the wheels must meet or exceed the weight limit of the tire. 8.25 wheels are the standard of the industry now. If you find an old 7.50 wheel, it was probably built before radials became popular and was designed for 11x22.5 textile tires and not radials. This was a big issue about 30 years ago when carriers started switching to radials, but most of the old wheels have been scrapped since then.