On this parts fiche the Washer,10.5x25x1.6 is the most specified component.
Some items from this specific schematic: Rim,rr,12x7.5at,f.s.b, Nut,flanged,10mm, Tire,rr,at25x10-12,kt, Valve.
The Wheels/tires is made up of components including this Tire,fr,at25x8-12,kt1 which is the most expensive.