+1 for shampoo if sealed, so it sounds like this will solve your problem. Obviously with a good mitt or maybe a wheel wooly.
If this doesn't cut it you can go for something more focused like bilberry wheel cleaner, which is a good performer at an excellent price. If there is serious contamination from brakes, then you might want to use iron-x or a similar iron fall out remover like dragon's breath, however you shouldn't need to be applying this type of product regularly. Different tools for different jobs.