Brush before the Friction Drive Roller?

A big inadequacy with my friction-drive (FD) system is the slippage, lack of friction, when the contact area is wet (because of the wet pavement).
So, I'm considering using a brush, a toilet brush maybe, to partially clean the tire before it contacts the roller.
I'm guessing it will help, and I should just rig one up. But has anybody tried this already?

pic irrelevant

BigBlue said:

How about a roller brush. I've seen ones that look like small roller paint brushes. How about something like an industrial roller brush:
http://motorbicycling.com/attachment.php?attachmentid=57232&stc=1&d=1362377802
...

Click to expand...

Since the tire is already rotating, I don't absolutely need a rotating brush, but if I had one of those, I'd mount it because it'll look cool spinning.