These wheels are designed to work with the Pololu 120:1 mini plastic gearmotors (offset output and 90-degree output) and the Solarbotics GM6 and GM7 gearmotors. They come in two sizes with diameters of 1.75" or 2", including the tire. The wheels are first laser-cut from 1/8" acrylic and then machined to have a groove for a 3/32" O-ring tire. The wheels securely press-fit onto the splined shafts of the GM6 and GM7 motors.
These wheels are packaged in sets of two plastic wheels and two O-rings. Both wheels are engraved with the Pololu part number on one side; they should be mounted with the engraved side facing the gearbox (the axle hole is slightly larger on that side, making press-fitting easier).
People often buy this product together with: