Choosing an in the bed fuel tank is one of those upgrades that completely changes how you use your truck for long hauls or heavy work. If you've ever found yourself white-knuckling the steering wheel while the "low fuel" light blinks in the middle of a desolate stretch of highway, you know exactly why these tanks are so popular. It's not just about having more gas or diesel on hand; it's about the peace of mind that comes with knowing you've got another 40, 50, or even 100 gallons ready to go.
Let's be honest, stock fuel tanks in most modern pickups are surprisingly small. You might get a 26-gallon or maybe a 36-gallon tank from the factory, which sounds like plenty until you hook up a 10,000-pound fifth-wheel trailer. Suddenly, your fuel economy drops into the single digits, and you're looking for a gas station every three hours. It's exhausting. That's where the in the bed fuel tank comes into play, effectively doubling or tripling your range.
Understanding the Two Main Types
Before you run out and buy the first shiny aluminum tank you see, you need to figure out how you actually want to use that extra fuel. There are generally two ways these things work: transfer tanks and auxiliary tanks.
A transfer tank is basically a giant portable gas can that sits in your truck. It has a pump and a hose, similar to what you see at a gas station. You use this to fill up other equipment—like a tractor, a skid steer, or even your buddy's truck when he runs out of fuel. It's not usually hooked up directly to your truck's engine.
An auxiliary tank, on the other hand, is plumbed directly into your truck's fuel system. These are awesome because they automatically keep your main tank full while you drive. You don't have to stop, hop out, and mess with a nozzle in the rain. You just keep driving while a gravity-feed system or a small electric pump does the work for you. Most people looking for an in the bed fuel tank for long-distance travel go for the auxiliary setup.
Material Matters: Aluminum vs. Steel
You're going to see a lot of debate online about whether to go with aluminum or steel. Honestly, both have their place, but they offer very different experiences.
Aluminum tanks are the gold standard for most hobbyists and long-haulers. They're lightweight, which is a huge plus because fuel itself is heavy (diesel weighs about 7 pounds per gallon). Aluminum also doesn't rust. Since condensation can sometimes build up inside a tank, having a material that won't flake off rust into your fuel filters is a big deal. Plus, they look great—that diamond plate finish gives the truck a rugged, professional look.
Steel tanks, however, are incredibly tough. If you're working on a construction site where things are being tossed into the bed or you're off-roading through tight trails, steel might be the better bet. It's usually cheaper than aluminum, too. The downside is the weight and the potential for corrosion over the long haul if the interior isn't treated properly.
The Trade-off: Losing Bed Space
We have to talk about the elephant in the room: an in the bed fuel tank takes up room. If you have an eight-foot long bed, this probably isn't a deal-breaker. You can tuck a 50-gallon tank right up against the cab and still have plenty of room for gear or a gooseneck hitch.
But if you're rocking a short bed (the 5.5 or 6.5-foot variety), things get a little cramped. You have to measure carefully. Many manufacturers make "low-profile" or "L-shaped" tanks specifically to solve this problem. An L-shaped tank is clever because the bottom part of the "L" slides under a standard crossover toolbox, allowing you to have both extra fuel and a place to keep your wrenches dry.
Why You Might Want a Combo Unit
If you're already worried about losing space, you should definitely look into combo units. These are essentially an in the bed fuel tank and a toolbox welded together into one piece. It's a very clean look. You get a locking storage chest for your straps, hitches, and tools on top, with the fuel reservoir sitting underneath it. It kills two birds with one stone and often uses the space more efficiently than if you tried to buy a separate tank and box.
Installation Isn't as Scary as It Sounds
I know the idea of drilling holes in your truck bed makes some people break out in a cold sweat. It feels wrong to take a drill bit to a vehicle you spent thousands of dollars on. But installing an in the bed fuel tank is actually a pretty straightforward Saturday afternoon project.
For a gravity-feed auxiliary tank, you usually just have to drill a few holes to bolt the tank down and one hole for the fuel line to reach the filler neck. Most companies sell a specific "install kit" that includes a T-pipe you splice into your factory fuel filler hose. Once it's all hooked up, gravity pulls the fuel from the bed tank into the main tank. It's simple, it's reliable, and there are no wires to mess with.
If you're going for a transfer tank with an electric pump, you'll need to do a bit of wiring to get power to the pump motor. It's still very doable for a DIYer, but you'll want to make sure your connections are solid so you don't end up with a blown fuse when you're trying to refuel in the woods.
Staying Legal and Safe
It's worth mentioning that there are rules about hauling large amounts of fuel. In the U.S., the Department of Transportation (DOT) has specific requirements for tanks used to haul flammable liquids. Most reputable in the bed fuel tank brands are DOT-approved, but it's always worth double-checking the labels.
Safety is also a big one. You want a tank with proper baffling. Baffles are internal walls that prevent the fuel from sloshing back and forth. If you have 50 gallons of liquid slamming against the side of the tank every time you take a corner, it can actually affect how your truck handles. Good tanks are designed to keep that liquid stable.
Is It Worth the Investment?
At the end of the day, an in the bed fuel tank is an investment. Between the tank itself, the installation kit, and maybe a pump, you're looking at anywhere from $500 to $1,500. That's a decent chunk of change.
But think about the benefits. You can shop around for the cheapest fuel prices rather than being forced to pay "highway robbery" prices at a remote truck stop. You can bypass the busy, cramped gas stations when you're towing a long trailer—which is a nightmare to navigate. Most importantly, you gain a level of independence. Whether you're heading out for a week of off-grid camping or you're hauling a load across three state lines, having that extra capacity makes the trip significantly less stressful.
If you spend a lot of time behind the wheel, you won't regret putting an in the bed fuel tank in your rig. It's one of those mods where, once you have it, you'll wonder how you ever managed without it. It turns your truck into a true long-distance machine, ready for whatever the road throws at you.