The tubeless equivalent of a 20" tube-type tire is a 22.5" tire. For instance, a 10.00-20 tire, and an 11-22.5 are the same height, and approximately the same width. I don't know if there is a direct-swap for a 8.25 X 20, but I don't think there is. It seems the tire dealer ruined at least one of your rims on purpose. There is no excuse for hitting a rim hard enough with a tire hammer to knock a hole in it! I have destroyed rims that were damaged beyond safe re-use, but I've done it by cutting big holes in them with a torch!
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!