[frizzen]

If you want ZZ rims on a Bit, get the "Performance Booster Upgrade Kit". 3 axles, 2 motors, 3 torsion bars. Nibble the end off the outer center of the rim so you can get a pin through it for your steering wheels. The rear axle is either a direct swap, or you have to nibble just a hair off the spacer opposite the gear. (I don't remember)

A while back someone turned the chrome 8-spokes into chrome 4-spokes. works best with a tiny saw and a file.

Hotwheels has some great rims/tires if you're not above a little drilling. Also some great ones for monsters.

Lego has some that work well for monsters, again drilling.