I have a caterpillar 70 scraper i love but the rear tires are 21.00-24 tires which are impossible to find , 21L-24 are availible but are 10" shorter in height and when ejecting dirt i hate to give up any height. I either need to find some good used 21.00-24 tires or convert to a 25" rim ( which will be difficult because these are not bolt on rims they are all part of the hub ,anybody have any leads that could help me ,thanks