I recently got a set of four of the 15-hole wheels for a W124, and set about the task of cleaning them thoroughly before I mount tires on them.

It finally has sunk into my head that cleaning wheels is the same as cleaning any other painted surface with a clearcoat, and that when you take that approach, you can really clean off all the accumulated brake dust that you really can't do with the tire on the rim.

This is the approach I have taken so far and have had excellent results.

1. Clean the wheel with Meguiar's Car Shampoo and H20.
2. Dry the wheel with a synthetic chamois.
3. Clay bar all accessible parts of the "face" of the wheel.
4. Meguiar's Clearcoat Paint Cleaner applied by hand.
5. 3M fine cut rubbing compound applied by a DREMEL with a felt pad into each of those 15 holes and into the lug nut holes. The DREMEL with the felt pad is key here in getting all of the brake dust off. Some wheels required me to use a medium cut compound to get the last bit of gunk off.
6. Two coats of Meguiar's paste wax applied by hand.

The results are really nice, and I plan to start using Kleen Wheels to keep them looking that way. I was surprised how many scuffs and what I thought were permanent marks on the flat center area of the wheel came off with the clay bar and the clearcoat cleaner. The felt pads for the DREMEL are about $3 for a set of 5, I went through about 10 pads doing all 4 wheels.

Many fun new uses for the DREMEL! Now my wife thinks I've totally lost it to put that much effort into having clean wheels. It was less than an hour per wheel, and it was worth the effort.