Ah Simple Green .... wait till you spray it on a clients uncoated wheels, and immediately etch them. After footing the bill for a 5000.00 set of custom forged wheels, you will get the picture. It is NOT safe for all wheel types, and guessing is not a good deal.
As I told Lauren, the P21S is about the safest and almost neutral PH soap offered. Not only because of German cars, but because almost all of them come with high dollar aftermarket wheels. Over time the P21S will keep wheels looking new (as will DP) but lets revisit those wheels after using storebought cleaners for a couple years. Ever seen clearcoat cake off, the white mess when clearcoat fails from acid ??
Lauren, if you truly want a super aggressive wheel cleaner, but one that I would consider ok, then consider Poorboys Spray Rinse. You MUST follow the directions exactly. Cool wheels only, wet wheels only, spray liberal. These is citric acid and only needs to be used once monthly. Rest of the time soap/water only.
As for the GTO owner ... all that work. Why not protect those inner barrels ?? Use some paint sealant, or better yet DP Wheel Glaze or Poorboys Wheel Sealant and get better life between cleanings ???