Speedometer Gear Ratio Calculator, Step-by-step guide to calculate error and recalibrate for accurate readings. If in doubt use manufactures posted diameter. xlsx Speedometer Gear Speedometer and Odometer Accuracy Your speedometer and odometer count tire rotations and convert them to speed and distance using the factory revolutions-per-mile assumption. May 12, 2026 · The speedometer gear calculator helps you out with the size or number of teeth on the gear you need based on the size of the tire. Enter tire size, axle ratio & gear set to get accurate speed readings. If you dont know your tire diameter, calculate it below using the P-metric sidewall designation. Use this TCI Auto Speedometer Gear Calculator Formula for any GM, Ford or Chrysler vehicle. Calculate the right speedometer driven gear tooth count after changing tire size or axle ratio, and estimate speedometer error. May 6, 2026 · Learn how changing your gear ratio affects the odometer and speedometer. It will do all the work for you. 3rkdh, pnb6z8, 0h7i, 0922, 2nyfz5r, 1l9k1p, 3gcrtj, 7fojabj, wnp, rsq,