Speedometer Calibrators & Calibration Tools

Changing your vehicle's tire diameter or gear ratio will affect the speedometer reading by under or over-reporting the speed. Recalibrating the speedometer gauge with a speedometer programmer is required in order to adjust the speedometer to the new tires or ring and pinion gears on late-model vehicles with computer-controlled gauges. Mechanical cable-driven speedometers require a special machine or changing speedometer drive and driven gears in the transmission.

Having the correct speedometer reading will prevent you from being pulled over due to speeding caused by an under-reporting speedometer. It will also help keep you from losing value on your vehicle due to over-reporting, which will cause the mileage on the odometer to read higher than you actually drove.

In most cases, changing a calibration speedometer reading on late model vehicles, where software programming is used, typically requires less than 15 minutes.

There are a few different ways to check auto speedometer calibration:

Changing speedometer calibration on late-model computer-controlled speedometers requires the use of a calibrator / programmer. Most programmers make changes based on the tire diameter or gear ratio, which can change based on user preference. The calibration is done by connecting the programmer to the computer connection that is typically found under the dash. Then, following instructions on the display and with a push of a button, the speedometer is recalibrated. Finally, a test drive will confirm the recalibration resulted in the correct speed displayed on the speedometer gauge. Mechanical speedometer calibration on older vehicles with a cable-driven speedometer requires the use of a speedometer adjustment device that demagnetizes the gauge to make it read faster or slower, depending on what is required. If your transmission has speedometer drive and driven gears, changing them will also correct speedometer readings.

Correcting your speedometer reading after changing your tire size or gear ratio on a late-model vehicle is easy to do with a simple connection to a programmer and the push of a button. JEGS offers the best speedometer calibration tool selection on the market. Browse our speedometer calibrator offering for trucks (for example, Ford F150) and cars (such as late-model Dodge Chargers) to keep your gauge accurate at a relatively low cost.