When I was restoring rims as a hobby, I went through every available stripping product I could get my hands on, and found that for powder coat, the gasket remover stuff worked faster and stronger than anything else, and I tried aircraft stripper, gel strippers, you name it. It was also MUCH cheaper. The problem I've found now is that most auto parts stores no longer carry it, so it may not be available anymore.
This is what the can looks like.
Some areas, like the small diamond shaped pits in that rim, took a few sprayings to get out. Any stripper you use will only be effective while it's wet. Once they dry, they're less effective if not completely ineffective. What you see in that pic didn't take 5 minutes to wrinkle up, and that's 20+ year old factory powder coat.