Just a little more food for thought, the 10R 22.5's that I bought were from a school fleet, the tire shop has that contract and at a certain age or wear depth they replace the tires, the steering tires have to be virgin (non-re-caps) so at a certain point they come off. You might check around locally to see who does your school fleet.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy