2018 GMC Sierra 3500 Truck Bed & Tonneau Covers

Heavy-duty trucks—like the hard-working GMC Sierra 3500 HD—deserve a tonneau cover that’s equally dependable. That’s where RealTruck comes in. We understand that Sierra 3500 owners have different needs and priorities than mid-size and half-ton drivers, such as versatility while towing heavy loads via bed-mounted hitches, security to keep tools and other valuable cargo safe, and durability when subjected to quick wash methods, like drive-through car washes.​

Whether you’re driving an aging-but-trusty workhorse or a brand-new, hyper-luxurious Denali with a MultiPro tailgate, RealTruck’s tonneau covers are engineered with ultimate compatibility in mind. And with hassle-free clamp-on installations, anyone, regardless of skill level, can install our tonneau covers on their Sierra HD with conventional hand tools—in under an hour in most cases.

RealTruck’s Sierra 3500 tonneau covers aren’t your average, mass-produced, poor-quality products. We specialize in precision engineering, flawless fitments, and unmatched durability—that’s the RealTruck way.​

No matter your needs, RealTruck’s Sierra 3500 truck bed covers excel. We offer various options and specialized features engineered to appeal directly to HD truck owners—from cargo expandability via T-slot rail integration, to hefty load ratings supporting up to 500 lbs, to auto-locking slam latches for security you’ll never have to second-guess. Proprietary tech includes:​

• Integrated T-Slot Utility: Several of RealTruck’s tonneau covers—such as the BAKFlip MX4 TS—offer cargo expandability via integrated T-slot side rails, which enable quick, easy mounting of T-slot accessories, including racks, gear mounts, and more.

• Extreme Load Ratings: Our hard-folding tonneau covers are rated for heavy loads—300-500 lbs evenly distributed—to withstand oversized cargo, stacked snow, and more.

• Automatic Slam Latches: Proprietary latch technology allows Sierra 3500 owners to secure the bed cover with the tailgate either opened or closed—especially for those with MultiPro tailgate-equipped trucks.

Q: Can I use these RealTruck Sierra 3500 bed covers with a 5th wheel or gooseneck hitch?

A: Worried about clearance between your truck’s in-bed hitch assembly and tonneau cover? Most RealTruck truck bed covers, including hard-folding options like the BAKFlip MX4 Gen 3 and retractable options like the RetraxPRO XR, provide enough clearance to eliminate interference.​

Q: Does a RealTruck GMC tonneau cover fit the Sierra 3500 Dually (DRW)?

A: Yes. So long as you order the bed cover for the proper bed length, the interior dimensions will remain the same. When ordering, be sure to specify whether your Sierra is a DRW or SRW, if prompted, as mounting hardware may differ from one bed to another.​

Q: Are Sierra 3500 Tonneau Covers Actually Waterproof?

A: While no bed cover is 100 percent waterproof, RealTruck’s tonneau covers employ integrated drainage systems, EPDM rubber weather seals, and precision manufacturing to ensure minimal water intrusion. For additional moisture protection, consider pairing your new tonneau cover with a tailgate seal, like the TruXedo TruXseal.​

Q: Do I have to drill holes for drainage tubes when buying one of these tonneau covers?

A: No. The Sierra 3500 has factory plugs at the front of the bed that can be removed to route the drainage tubes outside of the bed—no drilling required.​

Q: How do I measure my Sierra 3500 bed for a cover?

A: Measuring your truck for a tonneau cover is an easy but necessary process, ensuring you order the correct bed cover for your application. To calculate length, measure from the front of the bed (at the bulkhead) to the rear (at the tailgate).

​Learn more about accurately measuring a truck bed in our comprehensive RealSource™ guide.