The other writers are right: wax or a polymer product DOES make the surface of the polished alloy wheels slicker, and, therefore, easier to clean. I use NuFinish, an inexpensive mass-market product, about once every six months on the allow wheels, and it helps make brake dust easy to clean off with a wet sponge. Make sure you do remove brake dust regularly because that black stuff turns into a caustic glue over time and bonds permanently to your wheels. Checking the cleanliness of wheels is a quick to evaluate what type of owner a person is who is selling a car. If he can't be bothered to remove brake dust, do you trust the rest of his maintenance practices?