The 2015 GMC Sierra 2500HD pickup truck has a maximum towing capacity of 17,900 pounds when using a fifth-wheel hitch and trailer. The truck can tow up to 14,500 pounds using a conventional trailer hitch.
The 2015 Sierra 2500HD owes much of its towing capacity to its 6.6-liter turbocharged diesel engine. This engine produces 397 peak horsepower and 765 foot-pounds of torque and is mated to a reinforced Allison 1000 transmission. The Sierra 2500HD is also available with a 6.0-liter V8 gasoline engine, though opting for this engine reduces the truck's fifth-wheel towing capacity to 14,500 pounds and its conventional towing capacity to 13,000 pounds.