This is by far the best wheel cleaner I've ever used, and I've used them all. Just make sure to wash your driveway down after as it's pretty caustic stuff.

http://www.trans-mate.com/CarWashProducts.html#wheel

It really is a spray on hose off application. Also, it should be mixed 3 parts water to 1 part detergent. Easiest stuff ever and well worth the money!