Frequently Asked Questions

Variables to consider include tire size (especially if it’s changing), transmission ratio, rpm at cruising speed, the stock gear ratio, and the intended usage of the vehicle. The tradeoff here is off-the-line acceleration versus freeway-speed performance.

Re-gearing serves two purposes. It can re-gain lost drivability in daily driven vehicles that have bigger tires installed or custom tailor performance for a dedicated off-roader that doesn’t put as much emphasis on daily driving.

If you’re adding big tires, technically you’re already re-gearing your ride because the increase in tire circumference changes the final drive ratio. Think about it this way… if you’re running a 3.73 gear, the pinion gear rotates 3.73 times to turn the ring gear one full rotation. On the road a bigger tire will take more rotations to get up to speed (slower) but require a lower engine rpm to maintain a highway speed. In some cases, bigger tires can create profoundly adverse driving characteristics and a reduction in fuel efficiency.

To figure out what your rig is doing and how to pick the right ratio you need to know your gear ratio and tire height in stock trim. These factors can be used to determine your engine rpm at a given vehicle speed. Our homepage has easy-to-use calculators that compute gear ratio and tire height. Then you take those numbers and feed them into our RPM calculator.

Use your stock set-up as a baseline to see what your stock vehicle speed to engine speed relationship is. If your rig is a daily driver you’ll want to gauge performance at freeway speeds. If you’re dialing in a dedicated off-roader, freeway speed performance will be less critical so you may want to evaluate slower vehicle speeds. Once your baseline is established, enter your new tire diameter and adjust the gear ratio to best match the stock numbers for daily drivers or the desired performance of a dedicated off-roader.

Check out our calculators here.