Colson wheels aren't bad, but their traction isn't the best either.

If you have access to a manual mill with a rotary table, put some 1/4 inch plate on there, mill it round, punch some holes, then weld it into the center of a 4inch ID aluminum pipe. Poof, High-Tech traction wheels for cheap! If you're missing the Mill part, check out your local community college; many of them have shops and would love to help you out.