That looks like oxidation. I don't think there is any clear coat on those rims. A good buffing wheel or elbow grease with varying polishing compounds should bring it back to like new.
I was totally wrong - my wheels are indeed raw aluminium! I just spent a few minutes with a red Scotchbright pad, finishing with a dab of Solvol Autosol (been using that for 50 years) and voila! The trouble is, now I've made a clean spot so I'm going to have to finish the job now
I used Gords, and buffing pads and cones on a drill I'll post before and after, I never tried the White Diamond polish, but plan on it, mother's did absolutely nothing. GL
PS definitely read the directions, red shop towels, microfiber, steel wool, and wet/dry paper really help, and when and what order and time all do too.
I would get the Gords too, I thought it ate right threw the black, plus everything in the kit and some wet/dry it's only like $20
But I never used white diamond on anything so I wouldn't know, GL can't wait to see results, please post with pic's mine need a touch-up after the winter outside under a cover