10mm ø wooden dowel with 60 grit glued along it and elbow grease.
Using a gas torch (like the plumbers use) you can melt it and scrape it off with a bit of 15 mm copper tube and then sand it smooth. Best done outdoors as it stinks and you need to hold the wheel steady. Don't get the rim too hot as you'll melt the stickers on it.
The glue will bubble up and go soft, then you can scrape it off before it sets again.
If you're going to go down the chemical route, wear gloves. My brother in law used to clean car parts with solvent and melted his thumb nail. 20 years on it's still soft and gooey. Ugh!
Methyl Ethyl Ketone - Melts anything including your brain cells and body parts. Highly dodgy