Most likely it's brake dust. Are the insides of you wheels clear coated or just the outside? You don't want to use harsh abrasives on clear coat cause it will eat way at it. Since I have the chrome plated wheels, the best thing to clean my wheels with is non ammonia glass cleaner.

 

What would someone use on clear coat wheels?mine are showing something like water spots but it might be the clear coat turning loose.

 

I'd treat the clear coat on your wheels, like the clear coat on the paint. Use a very fine polish (nothing too abrasive) and remove it with a micro fiber cloth and see if that does the trick. Then I usually throw a coat of wax on them.

 

Can You use the Megs Ultimate Compound on Chrome Rims to remove scratches and then top with their hot rims chrome polish and finnish with a coat of NXT 2.0

 

Eagle 1 A2Z All Wheel & Tire Cleaner is the best stuff I have ever used. Try it out if you haven't yet.

 

I've used steel wool for the inside of my rims and for my exhaust tips. Works great on stainless steel and pretty dang good on chrome too, without any harsh scratching of any sorts. I used the wool just recently on my Monte's exhaust tips after I purchased it. I don't think they had ever been cleaned before...they looked brand NEW when I got done! I'm gonna have to try some of the other wheel cleaners offered here...

 

Somthing else you could do, and is what I did a long time ago with my ranger. You could go to the car wash fill up a gallon water jug with some wheel/engine cleaner and use that to scrub with a brush>>somthing that has brissles like a toothbrush.

 

They should be alu wheels so no rust. It just where the salt on the roads from winter can put pits in alu. I always get steel wool to the rear of my wheels and paint flat or satin black so this doesn't happen. You can still do that. It makes the wheels look better too and u dont have to clean behind it anymore its always black lol On the front just use soap and water and after wax with any carnauba wax for extra protectant.