I dont have a particular problem with keeping black wire wheels clean as I don't tend to go out in wet conditions and the car isnt used much in winter.
Admittedly wire wheels arent the easiest thing to clean whatever colour they are painted. It is only the same as having Black paintwork on a car though. It is difficult to keep a Black car clean but less so on a weekend only car and Black paintwork on a car looks superb when clean.
