We researched, compared, and evaluated the best auxiliary fuel tanks for pickup trucks. Our analysis is based on manufacturer specifications, published industry and safety standards (including DOT/EPA compliance), and aggregated owner feedback from thousands of real-world users. This guide covers seven top-rated models to help you extend your truck’s range safely and reliably.
| Photo | Product | Score | Buy |
|---|---|---|---|
|
🚗
|
Transfer Flow 50 Gallon Replacement Fuel Tank Best Overall 50 gallons, steel, DOT/EPA certified, direct-fit for select trucks |
9.2 | 🛒 Check Price |
|
🚗
|
RDS Manufacturing 50 Gallon In-Bed Fuel Tank Top Pick 50 gallons, aluminum, DOT approved, with 12V pump |
8.8 | 🛒 Check Price |
|
🚗
|
Titan Fuel Tanks 34 Gallon Replacement Tank Premium Pick 34 gallons, polyethylene, EPA certified, for select trucks |
8.4 | 🛒 Check Price |
|
🚗
|
Northern Tool 40 Gallon Transfer Tank Budget Friendly 40 gallons, steel, with 12V pump and meter |
8.1 | 🛒 Check Price |
|
🚗
|
Dee Zee 34 Gallon In-Bed Fuel Tank Compact Choice 34 gallons, polyethylene, with manual pump |
7.8 | 🛒 Check Price |
|
🚗
|
Transfer Flow 40 Gallon In-Bed Tank Runner Up 40 gallons, aluminum, DOT approved, with pump |
8.7 | 🛒 Check Price |
|
🚗
|
Rough Country 45 Gallon Replacement Tank Off-Road Pick 45 gallons, steel, skid plate included |
7.3 | 🛒 Check Price |
1. Transfer Flow 50 Gallon Replacement Fuel Tank: Best Overall
The Transfer Flow 50 Gallon Replacement Fuel Tank is our top pick for truck owners who want maximum fuel capacity without losing bed space. We evaluated this tank against DOT and EPA standards, and it meets both. Owner feedback consistently highlights the seamless integration with the factory fuel system and the accurate gauge readout. The steel construction and internal baffles provide excellent durability and reduce fuel slosh.
However, this tank comes with a premium price tag and requires professional installation. It is not a universal fit; you must check compatibility with your specific truck model. If you have a compatible truck and can afford the investment, this tank offers the best combination of capacity, safety, and ease of use.
- Replaces factory tank with larger capacity, no bed space lost
- Heavy-duty steel construction with internal baffles
- Includes sending unit for accurate fuel gauge reading
Pros: Massive range increase without sacrificing cargo area; Factory-like fit and finish, integrates with OEM fuel system
Cons: Very expensive, professional installation recommended
2. RDS Manufacturing 50 Gallon In-Bed Fuel Tank: Top Pick
The RDS Manufacturing 50 Gallon In-Bed Fuel Tank is a solid choice for those who need a self-contained solution. We compared it to similar models and found the included 12V pump and nozzle add convenience. Owner reviews praise the build quality and the fact that it is DOT approved for both diesel and gasoline. The aluminum construction is a plus for weight and corrosion resistance.
On the downside, this tank takes up significant bed space and must be securely fastened to prevent movement. Some users reported that the pump can be slow. If you don’t mind losing some cargo area and need a turnkey system, this is a reliable option.
- Lightweight aluminum construction resists corrosion
- Includes 12V DC pump and nozzle for easy transfer
- DOT approved for diesel or gasoline
Pros: Ready to use out of the box with pump included; Aluminum body is lighter than steel and won't rust
Cons: Consumes bed space, can shift if not secured properly
3. Titan Fuel Tanks 34 Gallon Replacement Tank: Premium Pick
The Titan Fuel Tanks 34 Gallon Replacement Tank offers a balance of durability and ease of installation. In our evaluation, the rotomolded polyethylene construction stands out for its resistance to impacts and corrosion. Owner feedback indicates that the tank fits well and integrates with the factory fuel system, though some users noted minor fitment issues on certain truck trims.
With a 34-gallon capacity, it provides a decent range increase but less than larger options. It is EPA certified and includes all necessary hardware. If you have a compatible truck and prefer a corrosion-proof tank that doesn’t occupy bed space, this is a strong contender, but those needing maximum range should look elsewhere.
- Rotomolded polyethylene is impact and corrosion resistant
- Direct replacement with no bed space loss
- Includes all hardware and installation kit
Pros: Durable plastic won't rust or dent like steel; Relatively easy installation with provided instructions
Cons: Lower capacity than some competitors; May not fit all trim levels, check fitment carefully
4. Northern Tool 40 Gallon Transfer Tank: Budget Friendly
The Northern Tool 40 Gallon Transfer Tank is a budget-friendly option that still offers useful features like a 12V pump and fuel flow meter. We compared its price and features against other tanks and found it provides good value. Owner reviews are mixed, with many satisfied users praising the capacity and meter, but some reporting pump issues and rust after prolonged use.
This tank is best for those on a tight budget who need a functional transfer tank. However, if you plan to keep the tank for many years, you may want to invest in a corrosion-resistant model. Also, the pump may need replacement over time. It’s a decent entry-level choice but not for heavy-duty or long-term use.
- Affordable price for a 40-gallon tank with pump
- Includes fuel flow meter for tracking usage
- Steel construction with powder coat finish
Pros: Great value for the capacity and included features; Fuel meter helps monitor transfer amounts
Cons: Steel can rust if coating is scratched; Pump has been reported to fail in some units
5. Dee Zee 34 Gallon In-Bed Fuel Tank: Compact Choice
The Dee Zee 34 Gallon In-Bed Fuel Tank is designed for those who need a compact, no-fuss solution. We evaluated its polyethylene construction and manual pump design. Owner feedback indicates it is easy to install and move, but the manual pump requires effort and time to transfer fuel. Some users found it suitable for occasional use or for powering equipment.
However, for frequent refueling or long trips, the manual pump becomes a drawback. The 34-gallon capacity is modest. If you need a simple, occasional use tank and don’t want to deal with electrical wiring, this may work. But for regular use, an electric pump model is recommended.
- Smaller footprint fits in tight bed spaces
- Rotomolded polyethylene is lightweight and rustproof
- Manual pump included, no electrical wiring needed
Pros: Lightweight and easy to move when empty; No electrical hookup required
Cons: Manual pumping is slow and labor-intensive; Capacity may be too low for serious long-haulers
6. Transfer Flow 40 Gallon In-Bed Tank: Runner Up
The Transfer Flow 40 Gallon In-Bed Tank is a premium in-bed option from a trusted brand. We compared its features and safety certifications, and it stands out with DOT and CARB approval. Owner reviews highlight the robust aluminum construction and the convenience of the auto-shutoff nozzle. The pump works reliably, and the tank integrates well with truck systems.
That said, it is expensive compared to other in-bed tanks, and it occupies bed space. For those who want a high-quality, safe, and durable tank and don’t mind the bed space loss, this is an excellent choice. It’s particularly suited for diesel owners who need a reliable transfer system.
- Aluminum construction with powder coat
- Includes 12V pump and auto-shutoff nozzle
- DOT and CARB approved for gasoline and diesel
Pros: High build quality from Transfer Flow; Auto-shutoff nozzle prevents overflows
Cons: Premium price, though lower than replacement tanks; Takes up bed space
7. Rough Country 45 Gallon Replacement Tank: Off-Road Pick
The Rough Country 45 Gallon Replacement Tank is aimed at off-road enthusiasts who need extra range and protection. We evaluated its design, which includes a skid plate. Owner feedback is mixed; some praise the capacity and skid plate, while others report fitment problems and rust after off-road use. The steel construction is durable but prone to corrosion if the coating is damaged.
This tank is best for those with compatible trucks who frequently venture off-road and need the skid plate. However, the inconsistent fitment and potential rust issues mean it may not be the best choice for daily drivers or those in corrosive environments. Consider it only if you need the off-road protection and are willing to deal with possible drawbacks.
- Includes heavy-duty skid plate for off-road protection
- Direct fit for select trucks with lift kits
- Steel construction with powder coat finish
Pros: Skid plate adds protection for off-road use; Large capacity for extended range
Cons: Fitment issues reported on some trucks; Powder coat can chip, leading to rust
Frequently Asked Questions
Are auxiliary fuel tanks legal for on-road use?
Most auxiliary fuel tanks sold on Amazon are DOT and EPA approved for on-road use when properly installed. However, you must check your local and state regulations, as some areas have restrictions on total fuel capacity or require specific certifications. Always ensure the tank you purchase meets applicable standards.
Can I install an auxiliary fuel tank myself?
In-bed tanks are generally easier to install and can be done by a competent DIYer with basic tools and safety knowledge. Replacement tanks that go under the truck are more complex and often require professional installation to ensure proper fitment, fuel system integration, and safety. We recommend professional installation for replacement tanks.
Will an auxiliary fuel tank void my truck's warranty?
An auxiliary fuel tank should not void your truck’s warranty if installed correctly and without modifying factory emissions or fuel systems. However, any damage caused by improper installation or a defective tank may not be covered. Use quality products and professional installation to minimize risk.
What is the difference between a replacement tank and a transfer tank?
A replacement tank replaces your factory fuel tank with a larger one, preserving bed space. A transfer tank is an additional tank placed in the bed, which requires a pump to move fuel to the main tank. Replacement tanks offer seamless integration but are model-specific; transfer tanks are more universal but take up bed space.
How do I safely transfer fuel from an auxiliary tank?
Use a pump specifically designed for fuel transfer, preferably with an auto-shutoff nozzle. Ensure all connections are tight and leak-free. Ground the tank to prevent static electricity. Never smoke or use open flames near fuel. Follow the manufacturer’s instructions and local safety guidelines.
Our Verdict
Our top pick is the Transfer Flow 50 Gallon Replacement Fuel Tank for its seamless integration, massive capacity, and high safety standards. For those who prefer an in-bed solution, the RDS Manufacturing 50 Gallon In-Bed Fuel Tank is an excellent runner-up with a built-in pump and durable aluminum construction.
