Long RV journeys through remote areas can be exciting—but also a little nerve-wracking when your fuel gauge dips close to empty. When you're towing a travel trailer, fifth-wheel, or toy hauler, the last thing you want is to worry about where the next fuel stop might be.
If you’re looking to reduce fuel-related stress on your trips, a smart solution is adding an auxiliary fuel tank to your tow vehicle. These tanks are designed to increase your fuel capacity, allowing for longer stretches between fill-ups and fewer unplanned stops.
Peace of Mind on Every Route
Whether you’re navigating unfamiliar highways or exploring off-the-grid campsites, having a larger fuel reserve means fewer interruptions and more time enjoying the journey. Auxiliary tanks are typically installed in the truck bed and feed fuel into the main tank, either automatically or through a gravity-feed system.
One of the most popular options for diesel RV tow vehicles is this auto transfer auxiliary tank system that sits directly in the truck bed and uses a smart electronic controller. It’s especially ideal for long-haul RVers with full-size diesel pickups.
They’re especially helpful for RVers traveling in regions where gas stations are few and far between—or when detours take you far off the beaten path.
Built for Towing Convenience
Auxiliary fuel tanks are designed with towing setups in mind, especially for RVers hauling fifth-wheels, travel trailers, or toy haulers. Low-profile tanks that sit below the bed rail are ideal for fifth-wheel configurations, as they won’t interfere with hitch operation or trailer clearance. For travel trailers, taller options—including combo units with built-in storage—can be used without issue.
Some tanks feature a wedge-style shape that fits neatly at the front of the truck bed while still offering higher fuel capacity. The angled design ensures maximum trailer clearance, making them popular among fifth-wheel owners. These tanks typically range from 30 to 100 gallons and meet safety certifications set by the Department of Transportation (DOT), confirming they’re safe for fuel storage and transfer during travel.
For RVers who want to preserve full use of their truck bed, this spare tire auxiliary fuel system offers a clever solution by replacing the spare tire underneath the truck with an auxiliary tank. It features an in-cab electronic controller for seamless fuel transfer.
Several manufacturers offer auxiliary fuel tank solutions that are custom-built for specific makes and models. This detailed guide includes a helpful list of manufacturers and compatible vehicle types—from Ford Super Duty and Ram HD to Toyota and GMC trucks—making it easier to find a tank system that’s built to fit your exact vehicle.
No matter the style, the best auxiliary tanks are those that offer extra range without sacrificing truck bed functionality or towing performance.
Automatic vs. Gravity-Feed Systems
When selecting an auxiliary tank, consider how fuel will be transferred. Gravity-fed tanks use a manual valve, which can be simple—but requires attention to avoid overfilling or spills. Pump-assisted systems offer more control and can even be operated with automatic sensors or smartphone integration, helping to ensure safe, consistent fuel transfer.
Regardless of the method, always check that the tank design meets current fuel transfer safety standards.
Avoid the Guesswork: Plan Your Fuel Stops
Even with extended range, knowing where and when to refuel is key to stress-free RV travel. Use trip planning tools that allow you to map fuel stops ahead of time and check for accessibility, especially when towing. Satellite views and user reviews can help confirm whether stations are RV-friendly before you arrive.
Go Farther Without the Worry
Adding an auxiliary fuel tank isn’t just about capacity—it’s about peace of mind, especially when towing. Whether you’re heading deep into the backcountry or just want fewer stops on your route, extending your truck’s range can turn a nerve-racking journey into a relaxed adventure.