2025 Ram ProMaster Transmission & Axle Gear Ratios

Transmission gear ratios

The 2025 Ram ProMaster is expected to carry over the same powertrain options as the previous model year, featuring a robust automatic transmission designed for commercial use. The primary transmission offered is a TorqueFlite 9-speed automatic transmission, optimized for efficiency and power delivery.

TorqueFlite 9-speed Automatic Transmission (948TE)

Available axle ratios

The Ram ProMaster offers a selection of axle ratios to cater to different needs, balancing between towing capability and fuel efficiency. These ratios dictate how many times the driveshaft rotates for every one rotation of the wheel.

How to identify your axle ratio

Identifying your Ram ProMaster's axle ratio is crucial for proper maintenance, parts ordering, and understanding its performance characteristics. For Ram vehicles, you typically look for an RPO (Regular Production Option) sticker.

For most Ram ProMaster models, you can find the RPO sticker on the inside of the driver's side door jamb or in the glove compartment. Look for a three-digit code that corresponds to the axle ratio. Common codes include "DMJ" for the 3.86 ratio and "DMH" for the 4.08 ratio. If you can't locate the sticker, a Ram dealership can provide this information using your VIN.

Towing vs MPG impact

The choice of axle ratio has a direct and significant impact on your vehicle's towing capacity and fuel economy. It's a fundamental trade-off:

• Numerically lower ratios (e.g., 3.86): These ratios mean the engine doesn't have to work as hard to maintain speed, resulting in lower RPMs at highway speeds. This generally translates to better fuel economy. However, the trade-off is reduced towing and hauling capability, as the engine will feel more strained when pulling heavy loads.

• Numerically higher ratios (e.g., 4.08): With higher ratios, the engine spins more revolutions for every rotation of the wheels. This provides greater torque multiplication, allowing the vehicle to accelerate more quickly and pull heavier loads with less effort. The downside is increased engine RPMs at highway speeds, leading to lower fuel efficiency.

For the Ram ProMaster, the standard 3.86 ratio is a balanced choice for general use, offering a good compromise between efficiency and capability. The available 4.08 ratio is specifically designed for those who frequently tow or carry heavy payloads, prioritizing power over fuel economy.

Common issues

While the Ram ProMaster is known for its durability, as with any vehicle component, the differential and axle can experience wear over time. Some common issues to be aware of include:

• Ring and pinion whine: A persistent whining noise that changes with vehicle speed or under acceleration/deceleration can indicate wear on the ring and pinion gears. This often necessitates replacement of these components.
• Carrier bearing wear: The carrier bearings support the differential carrier. If these wear out, you might hear a humming or growling noise, especially at certain speeds. Neglecting this can lead to more significant damage.
• Limited-slip differential clutch wear: If your ProMaster is equipped with an optional limited-slip differential, the clutch packs within it can wear out over time, leading to a loss of traction in low-grip situations or chattering noises during turns. Regular fluid changes can help prolong their life.

Maintaining the correct differential fluid levels and following the manufacturer's recommended service intervals are crucial to preventing these issues and ensuring a long lifespan for your ProMaster's drivetrain.

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