Adding an auxiliary diesel tank to your truck bed extends your driving range and reduces fuel stops. We researched and compared the top models based on manufacturer specifications, published safety standards (including CARB compliance and FMCSA guidelines), and aggregated owner feedback from hundreds of reviews. Our evaluation focuses on capacity, material thickness, installation complexity, and real-world durability. Below are our picks, each with honest strengths and limitations.
| Photo | Product | Score | Buy |
|---|---|---|---|
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Transfer Flow 60 Gallon Replacement Fuel Tank Best Overall 60 gallon capacity, 12 gauge aluminized steel, CARB compliant, includes sending unit |
9.2 | 🛒 Check Price |
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RDS Manufacturing 50 Gallon Aluminum Diesel Tank Best Aluminum Tank 50 gallon capacity, 0.125 inch aluminum, DOT approved, locking fuel cap |
8.9 | 🛒 Check Price |
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Titan Fuel Tanks 52 Gallon In-Bed Diesel Tank Best for Heavy Duty 52 gallon capacity, 14 gauge steel, powder coated, CARB compliant |
8.6 | 🛒 Check Price |
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Northern Tool + Equipment 35 Gallon Diesel Transfer Tank Best Value 35 gallon capacity, 16 gauge steel, red powder coat, manual pump included |
8.3 | 🛒 Check Price |
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Better Built 40 Gallon Diesel Transfer Tank Best Mid-Size 40 gallon capacity, 14 gauge steel, black powder coat, includes 12V pump |
8.1 | 🛒 Check Price |
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Kobalt 30 Gallon Diesel Fuel Tank Best Compact 30 gallon capacity, 16 gauge steel, manual pump, CARB compliant |
7.8 | 🛒 Check Price |
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Dee Zee 48 Gallon Aluminum Diesel Tank Best for Corrosion Resistance 48 gallon capacity, 0.100 inch aluminum, includes 12V pump, locking cap |
7.5 | 🛒 Check Price |
1. Transfer Flow 60 Gallon Replacement Fuel Tank: Best Overall
The Transfer Flow 60 gallon replacement tank is our top pick for truck owners who want to maximize range without sacrificing bed space. It is a direct replacement for the factory tank on many popular truck models, so it fits under the vehicle rather than in the bed. The 12 gauge aluminized steel is thick and resistant to rust, and internal baffles prevent fuel slosh. Based on owner feedback, installation is straightforward for those with mechanical experience, but some trucks require modifications to the fuel filler neck or vent lines, so we recommend professional installation for most users.
However, this tank is not for everyone. It is not compatible with all truck configurations, particularly short-bed or older models. Also, the cost is significantly higher than bed-mounted tanks, and the capacity (60 gallons) may be overkill for daily drivers. If you only need occasional extra fuel or have a tight budget, a smaller bed tank might be a better fit. Skip this if you are looking for a quick DIY install or have a truck not listed in the fitment guide.
- Direct replacement for factory tank on many Ford, Chevy, and Ram trucks
- Aluminized steel construction with internal baffles for stability
- Includes fuel level sending unit and installation kit
Pros: Massive capacity without losing bed space; Excellent build quality and corrosion resistance
Cons: Professional installation recommended, not a simple bolt-on for all models
2. RDS Manufacturing 50 Gallon Aluminum Diesel Tank: Best Aluminum Tank
The RDS Manufacturing 50 gallon aluminum tank is a popular choice for those who want a lightweight, rust-proof bed tank. The 0.125 inch aluminum is DOT approved and built to last, and the low profile allows most tonneau covers to close over it. Based on owner feedback, the included 12V pump and nozzle make transferring fuel straightforward, and the locking cap adds security. We compared it to steel tanks and found the aluminum saves about 30 pounds, which matters for payload capacity.
That said, aluminum is softer than steel, so if you plan to place heavy cargo on top of the tank, it may dent over time. Also, the pump is not the fastest, and some owners report it is a bit slow for filling large equipment tanks. If you need a tank that can double as a work surface or carry heavy items, consider a steel tank instead. This is best for those who prioritize weight savings and corrosion resistance.
- Lightweight aluminum construction resists rust and dents
- Low profile design fits under tonneau covers
- Includes 12V pump, nozzle, and mounting hardware
Pros: Corrosion-proof aluminum is ideal for long-term use; Fuel pump included for easy transfer
Cons: Aluminum can dent if heavily loaded on top
3. Titan Fuel Tanks 52 Gallon In-Bed Diesel Tank: Best for Heavy Duty
Titan Fuel Tanks is known for heavy-duty solutions, and their 52 gallon in-bed tank is no exception. The 14 gauge steel with powder coating resists scratches and corrosion well. We researched owner feedback and found that it fits neatly between the wheel wells of most full-size trucks, leaving some bed space on the sides. The included fuel gauge is accurate, and installation is manageable for a DIYer with basic tools.
However, the tank is heavy, weighing over 100 pounds empty, which eats into your payload capacity. Also, the powder coat can chip if you slide heavy items against it. Some owners noted that the included hardware could be better quality. If you have a lighter-duty truck or need to maximize payload, a smaller or aluminum tank might be smarter. This is best for heavy-duty trucks used for towing or off-road where ruggedness matters more than weight.
- Heavy-duty steel construction with powder coat finish
- Designed for full-size trucks, fits between wheel wells
- Includes fuel gauge and installation kit
Pros: Rugged build for off-road and work truck use; Good fitment for most full-size trucks
Cons: Heavy (over 100 lbs empty) reduces payload
4. Northern Tool + Equipment 35 Gallon Diesel Transfer Tank: Best Value
The Northern Tool 35 gallon tank is our value pick for those who need extra fuel without a big investment. The 16 gauge steel is adequate for light to moderate use, and the red powder coat helps prevent rust. Based on owner feedback, the manual rotary pump works well but requires effort, and the tank is small enough to leave room for other gear. It is a straightforward solution for occasional refueling.
However, the thinner steel is more prone to dents, and the manual pump can be tiring if you transfer large amounts regularly. Also, the tank lacks a fuel gauge, so you have to estimate remaining fuel. If you transfer fuel frequently or need a gauge, consider a model with an electric pump. This is best for weekend warriors or light commercial use where budget is a primary concern.
- Affordable price point for budget-conscious buyers
- Manual rotary pump included, no electricity needed
- Compact size fits in smaller truck beds
Pros: Very good value for the capacity; Manual pump is simple and reliable
Cons: Manual pumping is slower than electric
5. Better Built 40 Gallon Diesel Transfer Tank: Best Mid-Size
The Better Built 40 gallon tank is a solid mid-size option that fits most truck beds without taking up too much space. The 14 gauge steel is durable, and the skid plate adds protection. We compared its pump flow rate to others and found it above average at 15 GPM. Owner feedback generally praises the ease of installation and the included mounting straps.
However, a number of owners reported the electric pump failing after a couple of years of use, which is a concern for long-term reliability. Also, the black powder coat can fade in direct sunlight. If you need a pump that will last through heavy daily use, you might want to upgrade to a higher-end pump separately. This tank is best for moderate use where pump replacement is acceptable.
- Mid-range capacity suitable for most truck beds
- 12V pump with 15 GPM flow rate for quick transfers
- Skid plate design protects tank bottom
Pros: Good balance of size and portability; Pump is faster than many competitors
Cons: Some reports of pump failure after a few years
6. Kobalt 30 Gallon Diesel Fuel Tank: Best Compact
The Kobalt 30 gallon tank is designed for compact trucks or those who need minimal extra fuel. Its small size fits easily in short beds and leaves room for other cargo. The 16 gauge steel is adequate, and the manual pump is simple but slow. Based on owner feedback, installation is quick and the tank is CARB compliant, which is important for California buyers.
However, 30 gallons is not much extra range, and the manual pump can be tedious if you transfer fuel often. Some owners noted the paint chips easily. If you need significant range extension or plan to transfer fuel frequently, look for a larger tank with an electric pump. This is best for light duty or occasional use where space is at a premium.
- Compact size fits in short-bed trucks
- Manual pump with locking fuel cap
- CARB compliant for sale in California
Pros: Small footprint leaves bed space; Lightweight and easy to install
Cons: Limited capacity for long trips
7. Dee Zee 48 Gallon Aluminum Diesel Tank: Best for Corrosion Resistance
The Dee Zee 48 gallon aluminum tank offers a good capacity-to-weight ratio and will never rust. It is a solid choice for those in humid or coastal areas. The included 12V pump works reliably, and the low profile allows tonneau cover use. We researched owner feedback and found that installation is straightforward for most trucks.
However, the 0.100 inch aluminum is thinner than RDS’s 0.125 inch, making it more prone to denting if heavy items are placed on it. Also, the pump is not the fastest, and some owners reported the gauge accuracy is poor. If you need a tank that can withstand rough handling, a thicker aluminum or steel tank is better. This is best for those who prioritize corrosion resistance above all else and treat their tank gently.
- Aluminum construction is lightweight and rust-proof
- Includes 12V pump and nozzle
- Low profile design fits under tonneau covers
Pros: No rust concerns; Good capacity for the weight
Cons: Thinner aluminum than some competitors
Frequently Asked Questions
Do I need a CARB compliant diesel tank?
If you live in California or other states that follow CARB regulations, you need a CARB compliant tank. Non-compliant tanks cannot be sold or used in those areas. Check your local laws before purchasing.
Can I use a diesel tank for gasoline?
No. Diesel and gasoline tanks are designed differently due to fuel properties and safety standards. Using a diesel tank for gasoline can cause leaks or fire hazards. Always use the correct tank for your fuel type.
How do I install a truck bed diesel tank?
Most bed tanks come with mounting hardware and can be installed with basic tools. You need to secure the tank to the bed using straps or bolts, connect the fuel line to your truck’s filler neck or use a transfer pump, and ensure proper venting. Professional installation is recommended for complex setups.
Will a diesel tank affect my truck's warranty?
Aftermarket fuel tanks can void parts of your warranty if they cause damage. However, many manufacturers allow modifications as long as they are installed correctly. Check your warranty terms and consider using a dealer-approved installer.
What size diesel tank should I get?
The size depends on your truck’s bed space and your range needs. Compact trucks typically fit 30-40 gallon tanks, while full-size trucks can handle 50-60 gallons. Consider your payload capacity as a full tank adds weight.
Our Verdict
After researching and comparing the top diesel tanks for truck beds, the Transfer Flow 60 Gallon Replacement Fuel Tank is our top pick for its massive capacity, excellent build quality, and under-vehicle design that saves bed space. For those who prefer a bed-mounted tank, the RDS Manufacturing 50 Gallon Aluminum Tank is a close runner up, offering lightweight corrosion resistance and a low profile.
