Originally Posted by mrdivito
its not brake dust/dirt, its seems to be actual rust
Easy check. Will a magnet stick to the rim? Yes = Ferrous (steel). No = Aluminum.
Edit: Add: IF your wheels are steel (severe doubts), then you have more/better options to cleaning them up. I strongly suspect however that there aluminum. Aluminum rust (aluminum oxide) is the same color as aluminum. Hence, the dark areas are not aluminum or aluminum oxide. What it may be however is a stain. Aluminum is SOFT. If someone had used an abrasive prior, removing the clear and scuffing away the aluminum oxide, then as the new oxide is forming, it is available to pick up 'staining' agents. If the aluminum was gouged (micro grooves), then the staining agents can become deeply embedded. Also, are the wheels painted? Is the staining just on the paint? Figure out what the problem really is before deciding on a corrective plan is all I am recommending. Save yourself a ton of work (and grief!).