After Toyota claiming compliance with the SAE J2807 towing standards for more than three years, all the domestic fullsize truck brands essentially stood in a circle staring at each other saying "you first" for adoption of the J2807 standards, claiming that they would follow suit once crosstown rivals reported according to the standard. General Motors is now officially the first company to follow Toyota's lead in reporting according to the J2807 protocol for the 2015 Chevrolet Silverado and GMC Sierra 1500.
For many common models, it's resulting in a 400-pound decrease in maximum towing capacity, with an example being a two-wheel-drive double cab model with the 5.3L V-8 and 3.08 axle going from a rating of 6,900 pounds to 6,500 pounds. A double-cab four-wheel-drive with the 5.3L V-8 and 3.42 axle goes from 9,600 pounds to 9,200 pounds.
Even after adoption of the revised standards, 12 configurations of the Sierra and Silverado have a towing capacity of more than 10,000 pounds. The highest-rated 5.3L model is the double cab two-wheel-drive model with the 6' 6" box and 3.73 axle at 11,200 pounds, and the highest-rated 6.2L model is the double cab two-wheel-drive with the 3.42 axle with a towing capacity of 12,000 pounds.
The highest-rated crew cab models are two-wheel-drive models with the 5' 8" box, with the 5.3L/3.73 model rated at 11,100 pounds and the 6.2L/3.42 model at 12,000 pounds of towing capacity. The highest-rated four-wheel-drive models are the double-cab 6' 6" models, with the 5.3L rated at 11,000 pounds and the 6.2L rated at 11,900. The highest-rated crew cab four-wheel-drive models are the 5' 8" box, with 10,900 pounds for the 5.3L and 11,800 for the 6.2L. All of the models with the highest-rated towing capacity are equipped with the Max Trailering Package.
Source: General Motors