Tamiya Big Truck Option Spare Parts 57 Double Tire Hub RC Parts 56557 & No. TROP.57 Nuts, Black, 2pcs,

Replace the standard 4mm flange nuts included in the kit. Secure the wheel with the inner nut, then screw the outer cap onto the inner nut. The aluminum outer cap, which realistically replicates the shape of the hub nuts on a real car, further enhances the realism of the finished product.