This scene demonstrates a 2 wheeled vehicle with wheels rotating correctly based on the path of the vehicle.
These are my Zombie rigs (zombie model created by William Vaughan). The forum link contains some information about how to use them and how I created them.
Although I have updated my rigging process considerably since creating this, the basics are pretty close to what I still use today. The fancy rig includes additional controls for hand parenting and stretching limbs.
Click here to visit the Zombie Rig forum thread.