Cleaning up wheels

I am trying to get the alloy wheels on the 1980 Cordoba cleaned up. I have been able to get most of the crud off, but now there are these little brown specks all over the wheels. I was under the impression that the specks may have been baked on brake dust, but brake cleaner doesn't have any effect on the specs. I did try using some 0000 steel wool, and it does take it off slowly. Problem is, the brown specks are on grey area and I am concerned that if I use the steel wool on the grey areas, I will take the grey color off, which I would prefer to not do, as I am not sure I can get the correct shade of grey painted back on.

Does anybody know if there is some sort of chemical that can take the brown spots off without damaging the wheel or taking off the factory grey paint. If I have to sand/steel wool off the brown specks, does anybody know where I can get the correct grey color to repaint the wheels?

Kostas
Author: kkritsilas