Full Opening Truck Boxes: Types, Materials

What Are the Common Types of Full Opening Door Truck Boxes

A full opening door truck box refers to a storage container mounted on a pickup truck (usually in the bed) or on a commercial service body, where the door swings open completely—often 180 degrees—allowing unobstructed access to the interior. Unlike standard toolboxes with lids that lift only 45–90 degrees, full-opening doors give you full face access. The following types are distinguished by mounting location, door configuration, and intended cargo.

Cross-bed full opening boxes (saddle boxes). These sit across the truck bed, behind the cab, resting on the bed rails. Typical lengths: 60–80 inches (across the width of a full-size truck). The doors open either from the top (swing up) or from the front (swing toward the cab). A "full opening" cross-box often uses two doors—one on each side—each opening 180 degrees. The interior is divided into two compartments. These are used for storing long tools, ropes, towing straps, and jumper cables.

Side-mount boxes (underbody boxes). Mounted on the side of the truck bed, below the bed rail, or on a flatbed service body. These are long, narrow boxes (length 48–96 inches, height 12–24 inches, depth 12–18 inches). The full opening door is usually a lid that lifts 180 degrees and rests against the truck side. Some have gas struts to hold the door open. Used for storing shovels, rakes, fishing rods, and pipe fittings. Some models include dividers for organizing small parts.

Chest-style boxes (single large door). These sit directly on the bed floor (not on the rails). The full opening lid is hinged at one long side, and it opens 180 degrees, often folding flat onto the adjacent bed rail. These are used for heavy cargo like chain binders, hydraulic jacks, and portable generators. Because the lid opens flat, you can step on it without damage (weight limit 150–250 kg). They occupy the entire bed width, so they are best for trucks where the bed is not used for other cargo simultaneously.

Drawer-style with full opening front door (service truck boxes). Used on vocational trucks (electrician, plumber, mechanic). The box is deep (24–36 inches) and has a front door that swings 180 degrees, but inside there are sliding drawers that pull out over the door surface. The door becomes a work platform when open. These are specialty items, often custom-made. They cost 2–4 times as much as standard boxes.

Materials Used in a Full Opening Door Truck Box

Aluminum Alloys (most common, 70–80% of premium boxes). The primary material for full-opening truck boxes is aluminum alloy, typically 5052, 6061, or 5055052 aluminum (2.5–3.5% Mg, 0.25% Cr) is used for the main body because of its good formability and corrosion resistance. It has a tensile strength of 195–260 MPa depending on temper (H32 or H34). For full opening doors that need to resist flexing when open, manufacturers use 6061-T6 aluminum (1.0% Mg, 0.6% Si, 0.3% Cu), which has a tensile strength of 240–310 MPa and is harder than 505. The thickness of sheet metal ranges from 1.6 mm (0.063 inch) for economy boxes to 3.2 mm (0.125 inch) for heavy-duty boxes. A 2 mm thick aluminum door (0.9 m × 0.5 m) weighs about 2.8 kg. The hinges are typically stainless steel (304 grade) or zinc-plated steel. Aluminum boxes are usually coated with a clear anodized layer (5–10 µm thick) or powder-coated (60–100 µm thick polyester or epoxy). Powder coating lasts 5–8 years in salt-spray conditions; anodizing lasts 8–12 years but shows scratches more visibly.

Steel (for economy and heavy-duty versions). Steel boxes are less common (10–15% of the market) because they are heavier. A 1.5 mm steel cross-bed box (60×20×20 inches) weighs 35–45 kg, compared to 18–25 kg for aluminum. However, steel boxes are used in two situations: low-cost entry level (thinner steel, 0.8–1.0 mm, with a painted finish that rusts after 2–3 years) and extreme heavy-duty (3–4 mm steel for off-road utility trucks). The steel is usually hot-dipped galvanized (55 g/m² zinc coating) or zinc-electroplated (12–15 µm) before powder coating. Welded seams on steel boxes are a rust entry point; full opening doors on steel boxes often use riveted construction instead of welded to avoid heat distortion. The hinges for steel doors are welded directly to the box.

Polyethylene (HDPE) for corrosion resistance. Rotomolded HDPE (density 0.94–0.96 g/cm³) is used for boxes that will be exposed to road salt, fertilizers, or chemicals. HDPE does not corrode. The material itself is flexible; a 5 mm thick HDPE wall has similar stiffness to a 1.5 mm aluminum wall. For full opening doors, the hinge must be a continuous stainless steel piano hinge (2–3 mm diameter pin, 50 mm hinge leaf width) screwed into the plastic with thread-forming screws. The door may have internal ribs (molded into the plastic) to resist sagging when open. HDPE expands significantly with temperature: a 1.2 m long box at -20°C is 5–6 mm shorter than at 40°C. This affects the fit of the door seal. Therefore, polyethylene boxes have rubber bulb seals (closed-cell EPDM foam) that compress by 6–10 mm to accommodate thermal expansion.

Rubber seals and gas struts (components). Full opening doors rely on a continuous seal to keep out dust and rain. The seal is typically a hollow D-profile (EPDM rubber, 60–70 Shore A hardness) or a bulb seal (10–12 mm diameter). EPDM lasts 5–8 years before cracking from UV. Gas struts (nitrogen-filled, 100–300 N force) hold the door open. For a 0.7 m × 0.5 m aluminum door weighing 5 kg, two 150 N struts provide 300 N total, which is more than enough (the door weight is about 50 N, so the extra force is for opening assist). Struts are rated for 10,000–20,000 cycles. After 5–7 years, the gas leaks out, and the door will not stay open. Replacement struts cost $20–40 per pair.