Would be a great time to change out the internal speedometer ring gear if I needed to.

For what it's worth:

The number of teeth for a correct speedometer gear (the one that goes into the tailshaft, not this ring gear) is:

Gear teeth = (Ring Gear teeth * Tire RPM * Final Drive) / 1000

So my 31" tires have an RPM of 661 (calculated for 30.5"), my final drive is 3.00, and the blue ring gear is an 8 tooth.

Gear teeth = (8 * 661 * 3) / 1000
Teeth = 15.8, or a 16 tooth gear.
If it'd been something like 15.5, I know my speedometer would never be correct, and a 9 tooth ring gear may put it closer.

Owner caption October 2012 · Photo 594 of 1564