This custom-designed plastic wheel has a rubber tire measuring 1.65" (42 mm) in diameter and is designed to fit the output shafts on the Solarbotics GM11a/12a/13a/14a/18 style gearmotors
Looking for a beefy tire for your small 3mm shaft motor? This custom-designed plastic wheel has a rubber tire measuring 42 mm (1.65") in diameter and with an 8.2mm (0.32") grip width.
An interesting feature offered are the teeth on the inside of the hub can be used with a reflector sensor for encoder feedback.
These gearmotors should be mounted onto the side of the hub with the protruding teeth, as shown on the right. The output shaft will slide into the socket easily at first but will achieve a snug fit when pressed through to the other edge of the hub.
Note: Pololu designed these wheels to fit on their 9mm long motor shafts. As the Solarbotics shafts are a bit short (8mm), you may find better results by shaving off ~ 1mm of the hub interior so you can firmly set the set the shaft. Or mount the motor from the other side!