How to increase Zumo tread friction?

Hi all,

I’m using my Zumo for a sumo battle, and I’m noticing that the treads seem to slip in a head-to-head competition where two similar robots are opposing each other.

Aside from washing the tread, is there something I can coat the tread with to increase its traction?

We’ve found that wiping the Zumo treads with rubbing alcohol between matches is a good way to remove dust that reduces traction. Aside from that and making sure the robot weight is as high as the rules will allow, we do not have any suggestions for further increasing the traction of the treads.