There were a bunch of special tires and wheels for the desert troops. The Dodge weapons carriers that I used to collect had an 18" wheel for the desert instead of the normal 16, and then used the 18" tire from the amphibious GMC ducks. I actually found a set while in Mexico at a small junk yard back in the 90's, but they were rusted to death from the salt air. I assume they were never sold because what the hell else used 18" tires !