Gear and RPM Data

Tire Data
Final Gear Ratio: Tire Width in (mm):
RPM Limit:
Aspect Ratio:
RPM Max Power:
Rim Diameter (inch):

Tire Diameter:
Gears  Ratio Compound Tire dimensions (Calculated)
1st Side Wall Height (inch):
2nd Tire Width (inch):
3rd Tire Diameter (inch):
4th Tire Circumference (inch):
5th Revolutions per mile:
6th Revolutions per kilometer:

Shift Points, You can edit, copy and paste from the table below

Gear, Shift Point and Speed Calculator


This is a gear, speed and shift point calculator. Given a few bits of information on your drivetrain and tires it will computer shift points, max RPM. You can enter tire size by the standard profile numbers or by the tire diameter. Transmission gear selection can be from a list of some common gearboxes or enter the gear ratios (Up to 8 Speeds) manually.

The calculator outputs speed in each gear at 5mph intervals upto the max RPM. This is a text file for easy printing, just cut and paste into your word processor or text editor. It also computes charts for Gear Ratio Slope, RPM Gear Drop and a Shift Point Chart. Use this data to optimize your driving.

These charts are interactive, you can zoom, and click on various parts of the chart to read data at the mouse.

Double Click to reset the Chart back to normal zoom.

For Just the Simple Tire Size Calculator (TireCalc) Click HERE
GTSparkplugs Header
Click for Contact Page Click for Contact Page