If I understand the question right Cal78 wants to install tubeless radials. If that is what he wants to do, he needs to buy 22.5 open center wheels. I would recommend 8.25x22.5 wheels if he he has enough clearance on the steering axle. Second choice would be a 7.50x22.5 if he gets too close to the tie rod ends. The counterpart of a 9.00x 20 is a 10R22.5. Another option is using what we refer to as a low profile 22.5. The size is 295/75R22.5. Size wise they are about he same as a 9.00x20. 295/75R22.5 is the standard of the trucking industry now and therefor they can be bought both new and used at a more reasonable price than any odd size and they come in 14 and 16 ply rating.