Use the Gears to Count Movement with Sensors!
Evenly spaced holes near the edge, which can be used with a slotted optocoupler to measure velocity, acceleration or distance of the gear or vehicle. Holes can also be used to attach the gear to a wheel, pulley or other objects.
Gear A has a 9/16 in. diameter with 13 teeth, Gear B has a 3/4 in. diameter with 18 teeth, Gear C has a 1-9/16 in. diameter with 38 teeth and Gear D has a 2-11/32 in. diameter with 58 teeth. Set includes four center hole inserts to 1/8 in. and one insert to 2mm.
Same type of pneumatic-style rubber tire used on expensive radio controlled cars - the same quality, but at a fraction of the cost. The aggressive-looking spikes are popular for their looks but also functional because the turning/rolling resistance is virtually zero. This is especially useful for two-wheeled vehicles when one wheel is held stationary during a turn. At the same time, the spikes enable the tires to climb over obstacles. 75 x 20 x 38mm inner.