I'd use a post about 4" high sticking up from a square base with a 5/8" bolt welded straight up on the end of post. Mount a hub on it with 3 bolts sticking up. Then I'd make a crank handle that had an old drilled out hub on it that fit onto the studs and could turn the tire. I'd put that whole assembly into a metal pail that had tabs welded inside and nylon bristle brushheads ziptied to the tabs. Insert tire, mount crank handle, Fill with water and detergent and rotate tire. Remove, rinse, repeat, I can fab it if someone wants to pay me.