Gears And Crawl Ratio Calculators

Once you start modifying your truck for off-road you eventually get to the point where you want to modify your gearing. This page will help you figure out what gears you need when adding larger tires, how to calculate a gear ratio, or calculate your final crawl ratio.

Gears Needed After Adding Larger Tires

You will need to know your overall tire diameter in inches to use this calculator.

If you have metric size tires (LT265/70/17) you can convert them to inches by using the Tire Size Calculator & Size Chart.

This calculator will take your gear ratio and tire sizes and tell you what the effective gear ratio is. It will then recommend a new gear ratio. This recommended new gear ratio will return the vehicle to its original performance after adding larger tires. Obviously, you will have to round the new ratio to the closest available ratio.

Calculate Gear Ratio By Counting Teeth

Your axle gear ratio determines how many times your driveshaft rotates for every full tire rotation. For example, a 3.73 gear ratio requires 3.73 driveshaft rotations to turn your tires once around. You should be able to find your gear ratio listed on the axle tag, however, if that has gone missing, you can simply count the number of teeth on each gear and divide the number of ring gear teeth by the number of pinion gear teeth. So, if you don’t know your axle ratio, you could actually jack up the truck, turn your wheel by hand, and count how many times your driveshaft turns.

But what if you found a set of gears and don’t know the ratio? You can figure it out by counting the teeth on the ring gear and pinion and entering them here to find out what the ratio is.