GMC's 2011 Sierra heavy-duty pickups now have increased towing (21,700 pounds) and payload ratings (6,635 pounds). To accomplish the rise in towing capacity, the engineering team tested the Sierra HD over various terrains, grades and weather conditions. The pickups also received design and lab analysis as well as climatic wind tunnel testing to confirm stable handling and performance of the powertrain, drivetrain and brake components at maximum gross combined weight rating.
Rick Spina, GM Full-size Truck global vehicle line executive, said that in developing the Sierra HD, it had been focused on providing customers "the most capable heavy-duty trucks in the market" with some premium features and styling. Spina also revealed that its first set of capability tests confirmed that the team had surpassed the payload and towing targets by a large margin.
Engineers used higher strength steel for the cargo box sills to achieve the increased payload capacity. Extensive testing was done on the vehicles. "We encourage consumers to test drive the Sierra HD against the competition," said Spina. "Based on our test results, we are confident our HDs will prove to be the best choice for real-world towing and hauling needs."