Murray Woo

I have one of those 2008 C350 with the rear brake dust problem. Changed the brake pads, and I don't have the rear brake dust problem anymore. But the original brake dust that was left on the rear wheels (I admit I didn't clean the wheels frequently since they got dirty right away) refuses to come off. They are really baked-on, I've never seen anything like this. Claying, using Goo-Gone...don't work. Conventional cleaners don't make a dent. Must be some kind of chemical composition or something from those original brake pads. Any ideas? I have tons of brake dust specs all over the wheels that I can't get rid of. Major eyesore.

C300Sport

OK, this may seem obvious but you didn't specifically mention it....did you try wheel/rim cleaner? It usually melts the brake dust right off so I can't imagine the grime being so tough they wouldn't work.

RLE

Do not buy any generic wheel cleaner since you could damage the finish if you haven't already.

Your best bet is P21S Gel which is approved by all German car manufacturers and wheel makers.

Sportstick

Adam's Green Wheel Cleaner

nyca

p21s gel is your best bet, let it soak for a long period of time.

RickP330

Adams and P21S are both excellent choices. I find that stubborn stains will come out over time and repeated washings.
RickP

C300Sport

Once you get them all cleaned up, be sure to put a coating or two of a good quality wheel wax.

Uga Uga

+1

And then clean at least once a week, if possible. It makes cleaning them a lot easier.

Murray Woo

Got it. I doubt this will happen again since the new pads are different ones.