Ron, I take it you're trying to clean the rough sand cast center web area and not the polished lip.
If so and those are Magnesium I'd stay clear of Products like Eagle One Mag etch and or Lock-tite Alum brightener, Aluminum pre-paint etch cleaners as they will clean the wheel and remove material. (Wheel will foam like Alka-seltzer) and the polished lip will be dull and need re-polishing.
Strong Alkali cleaners like Simple Green and 409 (PH above 12) will have a similar result to the lip area and can have long term effects if not thoroughly rinsed
Safest is to mix one part dish soap (Not Dawn) to four parts water in a spay bottle. Spray wheel let sit 1-2 min and use a pressure washer off with water.
Simple Green is outlawed in aviation as it can cause Hydrogen Enbrittlement to metals (has caused catastrophic failures).
We do use Simple Green
Extreme across the industry though as it will not have an oxidizing effect on Alloys.
https://cdn.simplegreen.com/download...ionCleaner.pdf