public VehicleWheel addWheel(Spatial spat, Vector3f connectionPoint, Vector3f direction, Vector3f axle, float suspensionRestLength, float wheelRadius, boolean isFrontWheel) {
        VehicleWheel wheel = null;
        if (spat == null) {
            wheel = new VehicleWheel(connectionPoint, direction, axle, suspensionRestLength, wheelRadius, isFrontWheel);
        } else {
            wheel = new VehicleWheel(spat, connectionPoint, direction, axle, suspensionRestLength, wheelRadius, isFrontWheel);
        }
        if (vehicle != null) {
            WheelInfo info = vehicle.addWheel(Converter.convert(connectionPoint), Converter.convert(direction), Converter.convert(axle),
                    suspensionRestLength, wheelRadius, tuning, isFrontWheel);
            wheel.setWheelInfo(info);
        }
        wheel.setFrictionSlip(tuning.frictionSlip);
        wheel.setMaxSuspensionTravelCm(tuning.maxSuspensionTravelCm);
        wheel.setSuspensionStiffness(tuning.suspensionStiffness);
        wheel.setWheelsDampingCompression(tuning.suspensionCompression);
        wheel.setWheelsDampingRelaxation(tuning.suspensionDamping);
        wheel.setMaxSuspensionForce(tuning.maxSuspensionForce);
        wheels.add(wheel);
        return wheel;
    }
Add a wheel to this vehicle
@param spat the wheel Geometry
@param connectionPoint The starting point of the ray, where the suspension connects to the chassis (chassis space)
@param direction the direction of the wheel (should be -Y / 0,-1,0 for a normal car)
@param axle The axis of the wheel, pointing right in vehicle direction (should be -X / -1,0,0 for a normal car)
@param suspensionRestLength The current length of the suspension (metres)
@param wheelRadius the wheel radius
@param isFrontWheel sets if this wheel is a front wheel (steering)
@return the PhysicsVehicleWheel object to get/set infos on the wheel
jme3-jbullet/src/main/java/com/jme3/bullet/objects/PhysicsVehicle.java