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Use our Differential Gear Ratio Calculator page to determine the best ring and pinion gear ratio for your vehicle. Installation of the correct ring and pinion gear ratio will help optimize performance, fuel economy and overall driveability.
You need to know your actual tire diameter in order to work with the RPM calculator relevant to gear ratio.
Tire specifications usually follow a three number format, such as 275/75R16, where 275 is the WIDTH of the tire tread in millimeters, 75 is the ASPECT (or percentage of tread width to yield the sidewall height), and 16 is the WHEEL diameter. Using the numbers in this example, you’ll get a tire height of 32.24″.
The calculated value should be used only as a guideline for RPM calculations. Quite often, if you measure your tire diameter from the ground to the top of the tire, it measures less than the calculated value. It may “round up” closer to the calculated value while in motion. Tires with identical specifications that are made by different manufacturers may also have different actual diameters.
Truck and off road tires may have a specification like 30×9.5R15, where 30 is the tire diameter, 9.50 is the tread width and 15 is the wheel diameter. You don’t need the tire diameter calculator in this case.
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Use the RPM calculator to determine what RPM your engine will run based on gear ratio, tire diameter, transmission and MPH. You can try various combinations to come up with an appropriate combination of ring and pinion gear ratio and tire diameter for your vehicle. The RPM calculator should be used as a guideline for comparative purposes only. Your vehicle will probably run at different RPM’s than those you calculate. See What gear ratio do I need in FAQ for a discussion on choosing a ratio.
Find all of the gear ratios available for your vehicle in our Application Guides or call our staff of differential experts at (800)510-0950 for LIVE help.
West Coast Differentials stocks a huge inventory of OEM and Aftermarket Ring & Pinion Gear sets and orders placed before 4 PM Pacific Standard time usually ship the SAME DAY! We have the Differential Gears to match your budget and performance needs.
Enter the number of teeth on your ring and pinion gear set to find the gear ratio. Example: Ring Gear / Pinion Gear = Ratio
Need a replacement Ring & Pinion or want to change ratio for better performance?
We stock a huge inventory of OEM and Aftermarket Ring & Pinion Gear sets and orders placed before 4 PM Pacific Standard time usually ship the SAME DAY!
Ring & Pinion Gears
Installation / Repair Kits
Replacement Axle Shafts