2011 GMC Sierra 3500HD III (GMT900, facelift 2011) Extended Cab Long Box Dimensions, Size & Specs

The curb weight of the 2011 GMC Sierra 3500HD III Extended Cab Long Box ranges from 2838 kg to 3501 kg (6257 lbs to 7717 lbs), depending on specific configuration and optional equipment. This weight reflects the truck's readiness to drive without passengers or cargo. The maximum gross vehicle weight rating (GVWR), which includes the truck's own weight plus passengers, cargo, and towing load, ranges between 4854 kg and 5908 kg (10700 lbs to 13025 lbs). This robust weight capacity underlines its heavy-duty capabilities suitable for demanding commercial and personal hauling tasks.

The ride height or ground clearance of the 2011 GMC Sierra 3500HD III Extended Cab Long Box varies between 213 mm and 221 mm (8.4 inches to 8.7 inches). This clearance level is designed to help the truck handle rough terrain and obstacles commonly encountered in off-road and construction environments. With this ground clearance, the truck can navigate uneven surfaces and moderate off-road trails while reducing the risk of undercarriage damage. However, the heavy-duty build and longer wheelbase mean it's best suited for light to moderate off-roading rather than extreme off-road conditions.

The 2011 GMC Sierra 3500HD III Extended Cab Long Box comes equipped with several rim options, including sizes 6.5J x 17, 8J x 18. Correspondingly, tire sizes vary between 235/80 R17 and 265/70 R18. These tire and rim combinations are chosen to balance load capacity, durability, and ride comfort. Larger 18-inch rims with 265/70 tires offer improved grip and a more aggressive stance, benefiting towing and load handling, while the 17-inch rims with 235/80 tires can contribute to a slightly smoother ride with easier tire replacement cost.

When the rear seats of the Extended Cab are folded down, the 2011 GMC Sierra 3500HD III offers a luggage capacity of approximately 2138 liters (about 75.5 cubic feet). This significant cargo space illustrates the truck's versatility not only as a heavy-duty workhorse but also for transporting bulkier items when passenger seating needs to be minimized. The long box configuration enhances this capability by providing a larger bed space behind the cab, ideal for larger or longer cargo loads such as building materials, tools, or recreational equipment.

Fitting the 2011 GMC Sierra 3500HD III Extended Cab Long Box into a standard residential garage can be challenging. Given its length of 6337 mm (249.4 inches or roughly 20.7 feet), many typical garages, which average about 6 meters (20 feet) in length, might be too short to comfortably accommodate the truck, especially with room left for closing the garage door. Additionally, the vehicle's height of 1966 mm (77.4 inches) and width with mirrors open at 2436 mm (95.9 inches) can add complexity for narrower or lower garages. Owners often need larger or custom garages or to park outside to avoid space constraints.

Compared to its predecessor, the 2011 GMC Sierra 3500HD III (GMT900 facelift) generally maintained similar dimensions in length and width but included subtle refinements in design to improve aerodynamics and interior space. While the overall length of 6337 mm (249.4 inches) remained close to that of the previous generation, enhancements in ground clearance and interior capacity were designed to improve utility and comfort. The facelift likely brought incremental improvements to curb weight and payload capacity rather than drastic dimensional changes, ensuring continuity in the heavy-duty truck’s usability and market appeal.

In the segment of heavy-duty pickups, the 2011 GMC Sierra 3500HD III Extended Cab Long Box measures comparable in size to competitors like the Ford F-350 Super Duty and Ram 3500 models from the same era. With a length of 6337 mm (249.4 inches), it fits within the typical range for heavy-duty long box trucks, though some competitors may be a few centimeters shorter or longer. Its width with mirrors open at 2436 mm (95.9 inches) is also competitive, ensuring stability and road presence. Overall, the Sierra 3500HD holds a strong position dimensionally for towing, load capacity, and driver comfort compared to similarly classed vehicles.

The 'Extended Cab Long Box' configuration of the 2011 GMC Sierra 3500HD III combines a spacious extended cab with a longer cargo bed. The extended cab provides additional seating space behind the front row, often with smaller rear doors and extra legroom suitable for additional passengers or storage. The long box, typically exceeding 2 meters (around 8 feet) in length, offers enhanced cargo capacity compared to standard or short beds. This combination is ideal for users who need both passenger versatility and maximum hauling capability, making the truck practical for work and family uses.

The curb weight range of 2838 to 3501 kg (6257 to 7717 lbs) indicates the 2011 GMC Sierra 3500HD III is a robust, heavy-duty truck engineered for strength and durability. This substantial weight generally results in lower fuel efficiency compared to lighter vehicles, as more energy is required to move the truck, especially when fully loaded or towing heavy trailers. Handling can be affected as well; the truck's mass provides stability at highway speeds but may result in less nimble maneuverability in tight spaces or urban environments. Manufacturers optimize suspension and braking systems to manage these factors, ensuring safety and control under demanding conditions.