We present a novel way of modeling wheeled vehicles on outdoor terrains. Adapting concepts from dextrous manipulation, we precisely model the way that three dimensional wheels roll over uneven ground. The techniques used are easily adaptable to other vehicle designs of arbitrary complexity. Our modeling method is used to validate a new concept for design of off-road vehicle wheel suspensions, called passive variable camber (PVC). Simulation results of a three-wheeled vehicle with PVC demonstrate that the vehicle can negotiate an extreme terrain without kinematic slip, thus improving vehicle efficiency and performance.