A 22.5" tubeless tire will always have an equivalent-height 20" tube type tire. They're close enough in most cases that a 20 and a 22.5 can be run as duals on the same rear hub.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!