I wax my wheels with the car every time I do
the "major detail" and go back over them with
a detail spray (after cleaning) every time I
wash the car. Looks amazing (especially with
an application of the Meguiars tire gel). Do
this about once a week and your wheels (and
the car in turn) looks like a million bucks.
It takes about a week of driving to get real
amounts of brake dust back on the wheels, the
wax does a decent job of keeping it at bay.
T.