Step 1 - Select Transmission Type
This is pretty straightforward, select "Manual" for a manual transmission or "Automatic" for an automatic transmission.
Step 2 - Select Speedometer Drive Gear Teeth
Options:
Mustang rear gears from 2.73:1 all the way to 4.56:1, pick the ratio you currently have or are planning to install.
Step 4 - Select Tire Width
Your tire width is measured in mm. For example, if your tire size is 275/40/17, your tire width would be 275.
Step 5 - Select Tire Series
Your tire series, or aspect ratio, is measured in a percentage based off tire width. For example, if your tire size is 275/40/17, your tire series (aspect ratio) would be 40. This means your tire sidewall is 40% as tall as the tread is wide.
Step 6 - Select Rim Diameter
Your rim diameter is measured in inches. For example, if your tire size is 275/40/17, your rim diameter would be 17.
***** If you do not know, just send me the information and I can tell you IF the 20 Tooth will work for you.