For those interested in the math, here is how it works out;
180/70/16 tire (Touring) (theoretically) has 29.2" diameter or 81.43" circumference
(note that the 240/50/16 of the Roadster is slightly smaller and also in real World, the diameter will not be quite this big anyway)
Let's just call it 80" circumference as a 'better' approximation.
1 mile - (5280' x 12)" = 63,360"
So in one mile the rear wheel turns (63,360 / 80) = 792 times.
There is a 2.864 final drive ratio, so the shaft turns (792 x 2.846) = 2254 times in that mile.
There is a secondary ratio of 1.043 between the Helical Gears which takes it to 2366 at the Transmission Output Shaft which is rotating at (2268 * 1.043) 2366 times for every mile traveled by the rear wheel.
Now - the speed sensor is looking at that Transmission output gear and sees a pulse every time a tooth passes across the sensor; With 48 tooth gear that means (2366 * 48) pulses for every mile = 112,844 pulses for every mile
Again that is theoretical number - in real World DBR3T got 117,000 pulses over his measured mile and a Metric User got 68,682 pulses for 1km (on a Roadster)
(note 68682 * 1.61 = 110, 578)
