public Vector3f getCollisionLocation(Vector3f vec) {
        Converter.convert(wheelInfo.raycastInfo.contactPointWS, vec);
        return vec;
    }
returns the location where the wheel collides with the ground (world space)

@param vec storage for the result (not null, modified)
@return a location vector (in physics-space coordinates)
jme3-jbullet/src/main/java/com/jme3/bullet/objects/VehicleWheel.java