Use the following formula to calculate the Tire Rev. per Mile for the above formula.

Ensure your speedometer reads accurately and reliably with the TCI Speedometer Gears and Accessories line. Designed for a wide range of automatic transmissions like 700R4, TH350, TH250, and others, these components let you fine-tune the driven and drive gear ratios to match tire size, axle ratio, or transmission swap changes with confidence.

Each speedometer driven gear housing is precision-machined to replace OEM housings when you upgrade to larger tires or modify gearing. The housings drop into the removable portion of your tailshaft, and you get various tooth-count options (34-39 teeth, 40-45 teeth, etc.) to dial in speed accuracy after changes.

If you’re running a GM 700R4, you’ll want the correct speedometer drive gear that matches your drive gear’s tooth count to avoid misreadings. TCI offers drive gear options so you can maintain precise calibration after a transmission swap or ratio change.

These accessories not only improve accuracy, but also protect your transmission components: using the right housing prevents damage common with improperly meshed gears, reduces unwanted wear, and ensures your speedometer, odometer, and electronic systems are all aligned.

Don’t accept speed errors or guesswork—get the correct gear and housing. Whether you need a speedometer driven gear, a speedometer drive gear 700r4, or a 700r4 speedo drive gear, TCI’s selection helps you restore precision quickly. Add these TCI speedometer gears and accessories to your build and ride true, mile after mile.