Took both of my W211s through a car wash...garden variety brushless wash. As always happens, the automated wash does not clean off all the the brake dust...I just deal with that after the fact with a hose and microfiber cloth. This time, however, it looks as though the brake dust has somehow stained the rims. There are spots that just won't come off. So I'm assuming they are "trapped" under a layer of wax and/or clearcoat.

What's my best bet for getting the wheels clean? Thus far I've only tried a hose and a cloth.

__________________
06 E320 CDI "Benson", Platinum Blue on Grey, 189k mi, Stage 1 tune, tuned TCU
06 E320 CDI "Rutherford", Black on Tan, 170k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 141k mi, wastegate conversion

19 Honda CR-V EX 57k mi
Thirteen other MB's owned and sold
1961 Very Tolerant Wife

The dust may be iron from the brake rotors, not brake pad material.

Try clay bar, Mr.Clean Magic Eraser or a Meguiars wheel cleaner. With the wheel cleaner carefully select the correct version for the finish on your wheels as there are 3-4 types. The wheel cleaners can chemically release the stains if you're fortunate.

Good luck!!!

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Some time back, someone on the diesel forum recommended Lysol Lime and Rust toilet bowl cleaner. My W123 bundts are almost 40 years old. I used an old toothbrush to get into the tight spots. It seemed to do no harm and melted away all that residue.