The "307" designation stands for 3 axles at 7,000 lbs each. By spreading the load across six wheels instead of four, you get incredible towing stability and reduced "tongue weight" fluctuations. Standard for 2026 are torsion axles, which provide independent suspension for each wheel—a must-have for protecting sensitive equipment on rough job sites.

Because of the extra length and weight required for a triple-axle setup, the 307 steps up to a heavier 8" x 15 lb I-Beam construction. This frame is laser-cut and tapered using Diamond C’s Engineered Beam Technology, ensuring the trailer can handle the immense "frame-twist" forces that occur when turning a triple-axle unit.

To support the 21,000 lb+ GVWR, the 307 comes standard with 14-ply all-steel radials. With six tires on the ground instead of four, you have a much larger contact patch with the road, which improves braking performance and significantly reduces the risk of a "total disablement" if you have a single tire failure.

With the potential for high tongue weights, Diamond C includes the Simol 2-speed jack as standard. This allows you to quickly raise the leg when uncoupled, but switch to "low gear" to easily crank the trailer up even when it's fully loaded with a 9-ton machine.

Heavy equipment like mini-excavators creates massive "point loads." To prevent the floor from sagging between the frame rails, the 307 is built with I-beam crossmembers spaced every 12 inches. This is a significant upgrade over the 16" or 24" spacing found on economy brands.

The 307 features the GIANT V-tongue storage box. Because this trailer is often used for long-distance or heavy-duty hauling, the box is designed to hold not just chains and binders, but it is actually large enough to house a full-sized spare tire inside, keeping it protected from theft and UV damage.

Diamond C doesn't use thin sheet metal here. The 307 features a massive, single-piece triple-axle fender made of 3/16" diamond plate. These are super heavy-duty "drive-over" style fenders that act as a structural step and can withstand the rigors of heavy industrial use.

• THE WARRANTY 2.0: Just like the rest of the 2026 lineup, you get the 6-Year Structural Warranty and 2-Year Comprehensive (Bumper-to-Bumper) coverage. Most triple-axle competitors (like Iron Bull or PJ) only offer a 3-year frame warranty. For a trailer with this many moving parts (6 hubs, 6 brakes), that 2-year bumper-to-bumper protection is a massive financial hedge.

• The "Engineered" Edge: Triple-axle trailers are notorious for "tire scrubbing" during tight turns. Diamond C’s Engineered Beam frame is designed to flex slightly to absorb these lateral loads, whereas traditional "stiff" I-beams are more prone to weld-cracking over time.

• DM Coating System: With three axles, there is a lot of road debris and spray kicked up. The DM Difference Maker powder coat (with its zinc primer) ensures that your frame doesn't start rusting from the inside out after just one winter.