The R&D Department at the Nerf Fab Shop has finally found a solution from the rubber band treading to give vinyl, and, yes, plastic tires the needed grip for slot racing.
The first product TheBoyz applied to styrene wheels was a Dollar General product called Flexible Sealer, a rubber coating knockoff of the gunk used on the TV ad to make an air boat out of screen. It was messy, but worked. Unfortunately it wore smooth after 15 laps and the traction was bidding adieu.
Uncle Sal and the gang knocked it out of the park, however, with their next solution. A self-fusing, no-mess, silicone tape known as Miracle Wrap (used on pipes, grips on umbrellas, etc.) adhered to the plastic wheels without glue! The traction is great, and it still allows drifting in the corners. The NFS rubber band days are gone, hopefully. Used some good old pi x diameter calculations to cut sections suitable for the wheels. (Who said you'll never need that middle school geometry?) Make sure tape overlaps edges to keep it on wheel.
Big Vinnie claims the Flexible Sealer will work well on the track aprons, as soon as masking procedures are worked out to protect the track and it's walls. Would be easier to decant the stuff or go with Peter's suggestion of the pickup bed coating, perhaps.
Nerf