get the serrated aluminum traxxas lock nuts that fit the axles. i don't know what they go to, but the track i race at keeps them in stock because it's impossible to keep wheels on without them. if you use those and the aluminum hexes, you can clamp the wheels down extremely tight, and they don't budge. ever.

before i started using hazards, i got away with using the stock ones, but with the hazards, it became a necessity