20" tube type tires and 22.5" tubeless have the same overall height. If the tire shop guys in your neighborhood wear lace on their drawers like they do in a lot of urban areas, you probably won't find anyone man enough to work on the sectional rim a tube-type tire has to have. Find a few more 22.5's and get rid of the 20's unless you can find an oldtimer who's not afraid of sectional rims.
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!