OEM 18's discolored
 

So a while back I washed my car at home as always. Having a hard time recalling what I sprayed the rims with, it was either Nick's Professional All Purpose cleaner or some Iron-X product possibly by Adam's Polish. Anyways, shortly after, maybe the next I think, I noticed black spots on all 4 rims. It looks like a discoloration of some sort. Is there anything I can use or do at this point? I am not sure what happened, I have am leaning towards the Iron-X product to be the culprit. It almost looks like it ate in some spots the finish. Wheels are the OEM 18" duckfeet.

Same here, oem colors are 3 stage paint and default to black once initial coatings have been eaten by harsh products. Meguiars wheel cleaner (Purple bottle) is what i've resorted to.
Unfortunately there is nothing you can do but to paint them. Sorry.

Did you let brake dust sit on wheels long? And did you rinse wheelnoff first before using caustic cleaner on them

What ends up happening is a harsh reaction to the iron. The issue here could have been the temperature of the wheel.
Anything you spray on a hot wheel will stain/damage it.

Have you tried using polishing compound on it to see if stain will buff out or even tooth paste

The black that you're seeing is not a stain, this is the base that it's painted on the Wheel. For the wheel to have this color and needs to be painted black first and then it receives multiple Coatings silver and it's finalized with clear. If you're seeing black that means there is no more clear and no more silver polishing compound toothpaste or anyting will only affect the black if it removes the black you'll be left with aluminum. I'm sorry but only repainting will take care of this issue.

The 19inch wheels are very close to liquid graphite touch up paint, I've used it and you can tell if you take time and use a toothpick