[jyl]

Wire wheel chucked in a drill, removes the old glue in about 60 sec. Won't hurt the rim.

(Although I'd be careful if it is an anodized rim, you could scratch the anodization on the edge of the rim braking surface. I assume you don't care about scratching the anodization on the tub gluing surface, you're not one that thinks the anodization has a structural purpose.)