fclaridge,
I'm a little confused. The 22.5" tubeless wheels and tires were designed as a direct replacement fot the 20" tube type. If you have 9.00 x 20" tires the direct replacement would be a 10.00 x 22.5"...they both have the same diameter. If you have 10.00 x 20's then you need 11.00 x 22.5's. As long as the wheels have the same offset your clearences will be the same.
With that said, I have know knowledge on the 19.5" wheels and the disc brake that are available...
Mike B
