2025 GMC Sierra 3500 in Springfield, TN
The 2025 GMC Sierra 3500 HD is designed for individuals and businesses requiring consistent towing and hauling performance across varied environments. Built on a proven platform, it offers robust engine options, extensive towing capabilities, and configurations suited for a wide range of operational requirements. The 2025 GMC Sierra 3500 HD remains available in Regular Cab, Double Cab, and Crew Cab formats, with the option of single or dual rear wheels. Its mechanical systems, frame structure, and integrated technology are engineered to support extensive loads without compromising stability or functionality.
Engine Performance and Torque Output
Two powertrains are offered for the 2025 GMC Sierra 3500 HD. The standard gasoline engine is a 6.6-liter V8 featuring direct fuel injection, cast iron block construction, and overhead-valve architecture. It produces 401 horsepower at 5200 rpm and 464 lb-ft of torque at 4000 rpm. This engine operates with a compression ratio of 10.8:1 and utilizes variable valve timing for improved response.
The alternative is a 6.6-liter Duramax® Turbo-Diesel V8, which delivers 470 horsepower at 2800 rpm and 975 lb-ft of torque at 1600 rpm. This diesel configuration features a higher compression ratio of 16.0:1, common-rail direct injection, and a four-valve-per-cylinder arrangement. The diesel variant is designed for maximum torque delivery during load-pulling tasks and low-speed maneuvering. Both engines are matched with an Allison® 10-speed automatic transmission, designated 10L1000, which is calibrated for consistent torque handling and efficient gear progression.
Transmission System and Gear Ratios
The Allison® 10-speed automatic transmission utilizes a set of gear ratios optimized for torque distribution and fuel control under various load scenarios. The first gear ratio begins at 4.54, gradually tapering down to 0.63 in the tenth gear. Reverse mirrors the first gear at 4.54. This gear spread provides a balance between launch strength and highway efficiency. The final drive ratio is 3.73 for gasoline-powered models and 3.42 for diesel models, allowing alignment between axle rotation and engine load.
Payload Stability and Frame Composition
The 2025 GMC Sierra 3500 HD is engineered for heavy payload applications. Depending on configuration, payload capacity reaches up to 7290 pounds in gas-powered dual rear wheel models. Diesel-powered configurations with dual rear wheels support up to 6644 pounds. These figures are contingent on drivetrain layout, cab style, and bed length.
The truck utilizes a reinforced ladder frame paired with suspension systems configured to accommodate high static and dynamic loads. The front suspension employs short-long arms with torsion bars for independent wheel movement and durability under pressure. Rear suspension setups include semi-elliptic, multi-leaf springs. These vary between two-stage designs for standard payloads and three-stage versions in models equipped with the Max Towing Package or dual rear wheels.
Braking and Steering Technologies
Hydraulic power-assisted brakes are standard across the 2025 GMC Sierra 3500 HD range. The system incorporates a Hydroboost brake booster and four-wheel disc brakes with Anti-lock Braking System and Stabilitrak electronic stability control. Front brake rotors measure 14 inches by 1.6 inches. Rear brake rotors vary based on axle configuration, with 14.1 inches by 1.3 inches for single rear wheel models and 14 inches by 1.6 inches for dual rear wheels.
Steering response is managed through a hydraulic power-assisted recirculating ball setup. Digital Variable Steering Assist is included in select trims such as SLT, AT4, Denali, and Denali Ultimate. This feature modulates steering effort based on vehicle speed and towing weight.
Towing Ratings for Conventional and Fifth-Wheel Applications
Conventional towing capacity for the 2025 GMC Sierra 3500 HD reaches 20,000 pounds across multiple diesel-powered configurations. Dual rear wheel diesel trucks equipped with the Max Trailering Package offer a maximum fifth-wheel or gooseneck towing capacity of 36,000 pounds. Gas-powered models configured with dual rear wheels provide conventional towing up to 18,800 pounds and fifth-wheel capability of 18,450 pounds.
Trailering stability is further supported by the standard Trailer Brake Controller, which distributes braking force proportionally between the truck and trailer. Adaptive Cruise Control with trailering functionality is standard on higher trims such as Denali and AT4. This system adjusts following distance with the presence of a trailer, supporting consistent highway travel.
Cab Configurations and Cargo Bed Options
The 2025 GMC Sierra 3500 HD supports a range of combinations involving cab and bed styles. Regular Cab Long Bed and Double Cab Long Bed formats are available across single and dual rear wheel setups. This modular approach accommodates requirements for cargo space, passenger volume, and overall length.
Fuel tank capacity differs slightly between configurations. Most variants carry a 36-gallon tank for gasoline and diesel. Certain Double Cab and Crew Cab standard bed models include a 29.4-gallon diesel tank.
Dimensional Measurements and Wheel Specifications
Exterior dimensions for the 2025 GMC Sierra 3500 HD vary by cab and wheel configuration. Width is 81.85 inches for single rear wheel models and 96.75 inches for dual rear wheel models. Ground clearance peaks at 11.22 inches for single rear wheels and adjusts to 10.47 inches in dual rear wheel variants. The Crew Cab Long Bed model with dual rear wheels stands at 80.67 inches in height and spans a wheelbase of 172 inches.
Standard wheel sizes include 17-inch steel on entry configurations and 18- to 20-inch aluminum options on premium trims. Dual rear wheel setups feature forged aluminum wheels for additional strength. Tires are designed to support a range of terrain and operational needs, from all-terrain to on/off-road variants, including LT275/65R20E and LT235/80R17E.
Interior Dimensions and Occupant Space
Crew Cab models provide substantial space for occupants. Front headroom is measured at 43.03 inches, with 44.53 inches of legroom. Rear headroom reaches 40.12 inches, while rear legroom is 43.4 inches. Shoulder and hip room exceed 65 inches in both rows, allowing seating capacity for work crews or passengers during extended drives.
Interior features vary by trim but remain focused on utility and accessibility. Entry-level and mid-grade models prioritize operational functionality, while upper trims include more advanced control systems and comfort accommodations suited for extended usage.
Integrated Technology and Driver Assistance
The 2025 GMC Sierra 3500 HD includes a selection of features designed to assist with daily operations. Digital Variable Steering Assist, Park Assist, and Adaptive Cruise Control with trailering function are integrated into various trims. The Pro and SLE trims now support optional Front and Rear Park Assist through the 2025 GMC Sierra 3500 HD Pro Safety Plus Package. These systems are designed for consistent feedback and enhanced awareness during low-speed maneuvers or confined movement areas.
Stabilitrak electronic stability control works in tandem with trailer sway control and the brake system to maintain alignment and reduce lateral movement. These features contribute to safety during adverse conditions and help protect cargo integrity.