Nearly every full-size pickup owner has a unique use for his or her truck. And considering the GMC Sierra’s 19 different cab and box combinations, the veritable alphabet soup of models practically has its own language of acronyms.

Some of the most important truck acronyms for owners to know are gross weight ratings. Exceeding any of a truck’s weight ratings is unsafe, and it’s a driver’s responsibility to know and avoid exceeding them.

“Nearly every vehicle performance attribute is designed and tested to one or more gross weight rating,” said Robert Krouse, General Motors trailering engineer. ”Body and chassis structural durability, powertrain and driveline durability, handling, braking, thermal and propulsion performance are all validated to specific ratings. That’s why it’s so important for owners to understand those limits.”

• GAWR, or Gross Axle Weight Rating, is the maximum amount of weight that can be placed on either a truck’s front or rear axle, including the weight of the truck, driver, passengers, equipment and cargo. A higher front GAWR generally means more capacity for accessories like plows, while a high rear GAWR relates to a higher payload.

• GVWR, or Gross Vehicle Weight Rating, is the maximum amount of weight for the entire truck and everything in it. This number isn’t simply each axle rating added together; for that to work, the owner would have to precisely load so that each axle weight rating is met just as the overall vehicle rating is met, which isn’t possible in real world conditions. As a result, GVWR is always lower than the sum of each axle to account for changes in weight distribution.

• GCWR, or Gross Combined Weight Rating, is the maximum weight of a truck and an attached trailer, plus everything in each of them. Some of a trailer’s weight is supported by the truck – this is known as tongue weight – a GCWR isn’t simply the GVWR plus the trailer’s weight. When attaching a trailer, an owner should factor tongue weight into a truck’s payload capacity.

The 2013 Sierra’s highest GCWR is 30,500 pounds for a 3500HD Duramax DRW model. DRW, another truck acronym, applies only to 3500HD one-ton pickups. It implies a “dual rear wheel” option, as opposed to a “single rear wheel,” or SRW.

The option adds not only higher payload and weight limits, but also better stability with a large trailer attached. For a 2013 Sierra 3500HD 4x4 Crew Cab, a DRW option adds 5,700 pounds of available trailer weight rating and 1,011 pounds of payload capacity.