General Motors announced Tuesday that the new 2011 Chevrolet Silverado and GMC Sierra heavy-duty pickups have increased towing and payload ratings to 21,700 pounds of towing and 6,635 pounds of payload.

The new figures were achieved through ongoing development and testing, and make the Silverado and Sierra the most capable and powerful heavy-duty pickups in the segment.

Based on these improved capacities, the 2011 Silverado HD possesses segment-leading capability in horsepower, torque, conventional towing, 5th-wheel towing, and payload. 

Starting production next week, it becomes the most capable heavy duty pickup on the market.

"We encourage consumers to test drive the Silverado HD against competitive models," said Spina. "Based on our test results, we are confident the Silverado HD will prove to be the best choice for real-world towing and hauling needs."

The GMC Sierra HD is the segment leader in diesel horsepower and torque (397hp, 765 lb-ft), conventional towing (17,000 lbs.), 5th-wheel towing (21,700 lbs.), payload (6,635 lbs.) and maximum GCWR (29,200 lbs.).

Production for the Sierra HD begins next week at Flint Assembly in Flint, Mich., and customers can expect to start seeing the heavy-duty trucks on dealer lots shortly thereafter.