Sandblaster works the fastest if you don't have the time to sand every crook and cranny to do a good job. You don't even have to remove the tires unless it's a cabinet blaster and won't fit. I have sand blasted a lot of old tractor rims inside and out to clean them up for repainting. Make sure to use primer close to the same color first. If going black, they have black primer out there.
I used to use "naval jelly" or something like that for my motocross bikes years ago. Don't know if it's still out there or not. Try a Google search.
Troubleshooter