wheel-axle is part of:
    50%  axle
    50%  car
    40%  wheel

wheel-axle contains:

Full expansion for wheel-axle:
   100%  2x2 Plate w/ Metal Axle & Lg Tires
   100%  2x2 Plate w/ Metal Axle & Sm Tires
    80%  2x2 1-Wheel Landing Gear Axle
    80%  2x2 2-Wheel Landing Gear Axle (Front)
    80%  2x2 2-Wheel Landing Gear Axle (Side)
    80%  2x2 Landing Gear Axle in Tri-Set