A sample from the products for the Front Wheel (rm85lk3/lk4) include: Nut,m12x1.25x1, Tube Assy,wheel Inner, Disc,front Brake, Spoke Set,fr Wheel.
In this schematic the "Screw(6x22)" is used most often.
The Pin 20x20 is the cheapest item from this partsfiche.