Get the best performance for your vehicle by installing the ideal Ring and Pinion Gear Set. Big tires kill performance and mileage. Regain lost power and torque by installing the proper ring and pinion gear ratio. High performance vehicle owners can optimize top end speed or off-the-line response. Use our Differential Gear Calculators to calculate your actual tire size, RPM at a given speed for any Ring and Pinion Gear Set, or simply to identify the Gear Ratio that you currently have. Get it right with the Sierra Gear and Axle Differential Gear Ratio Calculators! Click HERE to use the Calculators!

Our new 2012 JK is here. The 2012 features a new powerplant, the 3.8L Pentastar V6 that produces 285hp and 240 ft/lbs of torque. Ours is equipped with a 5-speed automatic, and driveability is far better than the 2011 and earlier JK’s. Jeep is claiming increased fuel economy. Dana 44′s with electric lockers are standard equipment for the Rubicon JK’s.

Upgrades so far include a 3″ Teraflex suspension with a full set of adjustable control arms, Hanson Offroad bumpers front and rear, Hanson Rocker Guards, 35″ BFGoodrich KM2′s and a Warn 9.5 cti winch. We wanted to run the stock Rubicon wheels so we also installed a set of Spidertrax 1.5″ wheel spacers to eliminate any rubbing issues.

The new ProCal Module compatible with the 2012 model just arrived, so we changed the differential gear ratio to 4.88 without putting the Jeep into limp mode. The ProCal also allowed for recalibration of shift points, speedometer and numerous other features.