Image Item No. Description  42610c04 (Inv)  Wheel 11mm D. x 8mm with Center Groove with Black Tire 17.5mm D. x 6mm with Shallow Staggered Treads (42610 / 42611) Catalog: Parts: Wheel & Tire Assembly  56904c01 (Inv)  Wheel 30mm D. x 14mm with Black Tire 43.2 x 14 Offset Tread (56904 / 56898) Catalog: Parts: Wheel & Tire Assembly  56904c02 (Inv)  Wheel 30mm D. x 14mm with Black Tire 43.2 x 14 Solid (56904 / 30699) Catalog: Parts: Wheel & Tire Assembly