Polishing wheel on a 7,000 rpm grinder, with the brown cutting agent. Followed up with the white polishing wheel & white or green polishing agent. Then when all is looking good 2 coats of sharkhide. I have lots of alum diamond tread on trailers, dumptrucks, pickup boxes, & alum wheels, the trick is in the sharkhide. It's what truckers & boaters (saltwater marine) use to keep em shiny. Oh yeah get a visor for your face, & some old coveralls... you will be black head to toe. Napa sells an alum cleaner that will eliminate some of the cutting process. Spray on & wash off, start from the bottom & work up, as to not leave streaks in alum, keep it all "wet"