Motive Gear – Rusty's Off-Road Products

TIRE SIZE: When larger tires are installed, the overall diameter increases, which can affect the vehicle's performance. To compensate for the larger tires and maintain the optimal power and torque delivery, the gear ratio needs to be adjusted. Changing to a lower gear ratio (numerically higher) helps to regain the lost power and torque.

OFF-ROADING: Changing the axle gear ratio can provide better low-end torque and crawling ability, which is beneficial when navigating steep inclines, rock crawling, or traversing through mud or sand. Lower gear ratios (higher numerically) offer increased torque multiplication, making it easier to conquer obstacles.

TOWING & HAULING: If you frequently tow heavy loads or haul significant cargo in your Jeep, changing the axle gear ratio can improve its towing and hauling capabilities. A lower gear ratio allows the engine to operate at a higher RPM range, providing more power and torque, which is useful for pulling heavy loads.

FUEL EFFICIENCY: Although it may seem counterintuitive, changing the axle gear ratio can also be done to improve fuel efficiency. By opting for a higher gear ratio (lower numerically), the engine operates at lower RPMs during highway cruising, which can result in improved fuel economy. This change sacrifices some low-end power but can benefit those who do a lot of highway driving.

PERFORMANCE UPGRADE: Some Jeep owners modify their vehicles with performance upgrades, such as adding a supercharger or installing a larger engine. In such cases, changing the axle gear ratio can help optimize the power delivery to match the increased horsepower and torque output of the upgraded components.

It's worth noting that changing the axle gear ratio can have an impact on other aspects of the vehicle's performance, such as speedometer accuracy and transmission shifting points. It's crucial to consult with a knowledgeable mechanic or automotive specialist who can help determine the appropriate gear ratio change based on your specific needs and vehicle configuration.

There are many factors that go into the choosing the right gear ratio including engine, transmission, tire weight, axles, cargo weight, trailer weight, elevation and the type of off-road trails the vehicle will see. For example, the Rubicon and Max Tow models have 4.10 stock gearing to handle the advanced off-road trails and high tow weight compared to the 3.73 stock ratio in the Sport and Overland models.

As a general rule for a Jeep equipped with the 3.6L engine and automatic transmission, we recommend 4.88s for 33-35” tires and 5.13-5.38 for 37-40” tires.

Manual transmissions, more aggressive trails, heavier cargo and larger towed objects may call for even lower gearing/higher ratios. Those looking for better gas mileage and anticipating less off-road use can look to higher gearing/lower ratios.

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