Good luck trying to find a drop center 15" wheel for tubeless tires that will fit over the massive brake drums on that C20. You'll probably have to special order some that move the tread center way outboard. That does pretty radical things to steering geometry. There's just barely enough clearance for the drums with the straight-barrel 15" tube type wheels.
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!