Are you talking about the rim/wheel or the rotors? Sorry I am a little confused by the posts. If the wheel I use this
http://www.autogeek.net/easy-detail-brush.html
works fantastic on my wheels (HRE P101's) you can get the whole inner lip of the wheel no problem. I also always dry my wheels off with leaf blower to make sure to get all the water out so there is no dripping etc.. which can build up in the lip while the car sits