No need to sand them. Scuff them really well with a scotch brite pad, clean with acetone or isopropyl alcohol and paint with wheel paint.
If yours is truly brake dust, a product called Iron-X will dissolve it. It's expensive though and you need to remove the wheels because that stuff will react with any iron it gets sprayed on.
If yours is truly brake dust, a product called Iron-X will dissolve it. It's expensive though and you need to remove the wheels because that stuff will react with any iron it gets sprayed on.