To take it one step further measure the frame and then check local junkyards for a newer school bus, they keep the spacing pretty common with the commercial stuff. That could get you way newer brakes\seals etc. but not quite up into the air brake sized stuff most MDT's have. Buses also usually have 1 piece 20-22.5 wheels. You can get 8.25 or 9.00r20 tires online pretty easy with places like simpletire, prioritytire etc but if you can find the 22.5's it's much easier to find tires local or if you are out along the rd with a flat.
https://buytruckwheels.com/products/...IKbCs8Iah7mAes
If you keep the stock axles the military also used that large 6 bolt pattern for 2.5T trucks and trailers so there are plenty of those wheels out there but watch, some are split ring rims still.