Here's the drill brush I was looking at - looks like a good deal (I have NO affiliation):
Drill Brush
Now I think the above would be great especially if it can get to the back of the wheel beyond the spokes.
[Also] I just happen to have a Shark portable steam cleaner so tonight I decided to haul it outta the basement to see how it would do. (I saw another thread in here about steam cleaners but never though of using the one we have on the cars)...
Well, it did a good job on the face of the wheel and in the crevice around the lugs. It did not do a good job on the wheel behing the spokes - that looks to need some cleaner to remove the
grime. I think the steam cleaner may come in handy in some other tough areas.