2025 Ram 2500: Transmission & Axle Gear Ratios

Transmission Gear Ratios

The 2025 Ram 2500 is available with two primary engine options, each paired with a specific heavy-duty automatic transmission engineered to handle its unique power and torque output.

8-Speed 8HP75-LCV Automatic (6.4L HEMI® V8)

This sophisticated eight-speed automatic transmission is standard on trucks equipped with the 6.4L HEMI® V8 engine. It offers a wide spread of ratios to provide excellent launch characteristics, strong acceleration, and efficient highway cruising.

6-Speed 68RFE Automatic (6.7L Cummins® Turbo Diesel)

For the legendary 6.7L Cummins® Turbo Diesel, Ram utilizes the robust 68RFE six-speed automatic transmission. This unit is built to manage the immense torque of the diesel engine, prioritizing strength and reliability for demanding towing and hauling tasks.

Available Axle Ratios

Choosing the right axle ratio is crucial for tailoring your truck's performance to your specific needs, whether that's maximizing towing capacity, fuel efficiency, or finding a balance between the two.

How to Identify Your Axle Ratio

Knowing your truck's specific axle ratio is essential for maintenance, ordering parts, or verifying its towing capabilities. Here are the primary methods for identifying it on your Ram 2500:

• VIN Decoder: The easiest modern method is to use an online VIN decoder. Simply enter your 17-digit Vehicle Identification Number, and the tool will provide a comprehensive build sheet, including the factory-installed axle ratio.
• Axle Tag: Most Ram trucks have a small metal tag bolted to the differential cover (the pumpkin-shaped housing in the middle of the rear axle). This tag contains codes and numbers that identify the gear ratio, differential type (e.g., open or anti-spin), and manufacturer. The ratio is often stamped clearly (e.g., "3 73" for a 3.73:1 ratio).
• Door Jamb Sticker: Unlike GM vehicles, which list RPO codes on a glove box or door jamb sticker, Ram trucks do not typically list the axle ratio code in this location. The VIN decoder or axle tag are the most reliable methods.

Towing vs. MPG Impact

The axle ratio has a direct and significant impact on both your truck's towing ability and its fuel consumption. The relationship is a trade-off:

• Numerically Higher Ratio (e.g., 4.10:1): This is known as a "shorter" gear. The engine needs to turn more times for each rotation of the wheels. This multiplication of torque makes it much easier to get a heavy load moving from a standstill and pull trailers up steep grades. The trade-off is higher engine RPM at highway speeds, which leads to lower fuel economy.
• Numerically Lower Ratio (e.g., 3.73:1): This is known as a "taller" gear. The engine turns fewer times for each wheel rotation. This results in lower engine RPM during highway cruising, which improves fuel efficiency. While still incredibly capable, it won't offer the same raw, low-speed pulling power as the shorter 4.10:1 gear.

For the 2025 Ram 2500, the 4.10 axle is the clear choice for those who will be frequently towing heavy trailers near the truck's maximum rated capacity. For users who do more unloaded highway driving or only tow moderate loads occasionally, the standard 3.73 ratio offers a superior balance of capability and efficiency.

Common Issues

While the AAM (American Axle & Manufacturing) axles used in Ram Heavy Duty trucks are known for their durability, a few issues can arise over a long service life, particularly under heavy use:

• Pinion Bearing Whine: A high-pitched whining noise that changes with vehicle speed (not engine RPM) can be a classic sign of a worn pinion bearing. This is often the first component to show wear in the differential.
• Carrier Bearing Failure: A rumbling or grinding noise, especially noticeable during turns, may indicate worn carrier bearings. These bearings support the differential carrier inside the axle housing.
• Limited-Slip Clutch Wear: On trucks equipped with the optional anti-spin (limited-slip) rear differential, the internal clutch packs can wear out over time. This may present as a chattering or groaning sound during tight, low-speed turns. A fluid change with the correct limited-slip friction modifier additive can sometimes resolve this, but clutch pack replacement may be necessary.

Proper maintenance, including regular differential fluid changes with high-quality gear oil, is the key to preventing these issues and ensuring a long, trouble-free service life for your driveline.

Need to diagnose a driveline noise or service your axles? Find a trusted, independent driveline shop in your area on Repairius.