• Ask TFLtruck: Ford F350 Dually – Which Rear Axle is Best to Tow a Camper Across Country?

    2018 ford f350 super duty
    2018 Ford Super Duty (photo: Ford)

    Which rear axle ratio is best for towing a large camper trailer across the country?

    Fred writes:

    I am looking to get a 2019 Ford F350 dually. What rear axle ratio would be best for a large 5th wheel camper cross country trip?

    The new Super Duty diesel comes with three rear axle ratios: 3.55, 4.10, and a 4.30. Take a look at the Ford’s towing guide chart below. The higher the numerical number of the ratio, the truck is said to have “lower gearing”. Having a 4.10 rear axle ratio means the drive-shaft spins 4.1 times per one revolution of the axle shaft that is going to the wheel.

    Truck makers are able to rate the trucks at a higher towing capacity with lower gearing. The maximum towing for the Super Duty with a 6.7L Power Stroke diesel V8 and a 3.55 axle is 27,300 lbs. The rating goes up to 31,800 lbs with a 4.10 axle, and up to 32,500 lbs with 4.30 gearing.

    Lower gearing also means the truck is able to get off the line a little better and negotiate steep mountain passes with a little more ease. On the flip side, the lower axle ratio takes down your fuel economy. The engine has to work a little harder to move the same distance.

    A gross combined weight rating of a large 5th wheel camper trailer is around 20,000 lbs. This is a weight of a fully loaded trailer. A F350 or F450 dually are required to carry so much tongue weight (likely over 4,000 lbs of tongue weight). However, having a 4.10 rear axle is not a must for a 20,000 lbs trailer. The 3.55 can get the job done and provide a little better fuel economy down the road. If you do want a little extra oomph to climb and descend the Rocky Mountains, then go with the 4.10.

    If you want to know more about towing heavy trailers with the latest 1-ton dually trucks, check out this video where we measure fuel economy on all three newest diesels.

    Andre Smirnov
    Andre Smirnov
    Andre Smirnov is an Automotive Enthusiast, Producer, Reviewer, Videographer, Writer, Software Engineer, Husband, Father, and Friend.