P215 doesn't work
 

I bought some of that gel brake dust cleaner to get rid of baked on brake dust on the rear wheels of my 2008 C350. This was before the brake pad change, in which the pads were making brake dust like mad. Well, I got tired of cleaning the wheels and now they are baked on, and didn't really make too much difference with the P215. Is there anything stronger that's safe for the wheels? Thanks.

P21S is quite strong. I've used it on wheels that have had brake dust baked on for months and it had no issues cleaning them up. How long did you let it sit on the wheels for? Did you use a brush to agitate it? It's not one of those spray on and hose off type of wheel cleaners.

I did...let it sit for two hours, brushed it with a wheel brush. Nothing. Even claying it didn't work. The original brake pads on the car must have been some super crap. No wonder Mercedes recalled them.