A thanks to Rustic Eagle (Bob) for contributing to this thread
Trailer Towing Weight Definitions
Base Curb Weight - Weight of the vehicle including a 150lb driver, full tank of fuel and all standard equipment. It does not include passengers, cargo or any optional equipment
Cargo Weight or Payload - Includes all weight added to the Base Curb Weight -- including cargo and optional equipment. When towing, trailer tongue weight is also part of the Payload Cargo Weight.
Gross Axle Weight (GAW) - The total weight placed on each axle (front and rear). To determine The Gross Axle Weights for your vehicle and trailer combination, take your loaded vehicle and trailer to a scale. With the trailer attached, place the front wheels of the vehicle on the scale to get the front GAW. To get the rear GAW, weigh the towing vehicle with trailer attached, but with just the four wheels of the vehicle on the scale. You get the rear GAW by subtracting the front GAW from that amount.
Gross Axle Weight Rating (GAWR) - The total weight each axle (front and rear) is capable of carrying. These numbers are shown on the Safety Compliance Certification Label, located on the left front door lock facing or the door latch post pillar. The total load on each axle (GAW) must never exceed its GAWR.
Gross Combination Weight (GCW) - The weight of the loaded vehicle (GVW) plus the weight of the fully loaded trailer. It is the actual weight obtained when the vehicle and trailer are weighed together on a scale.
Gross Combination Weight Rating (GCWR) - The maximum allowable weight of the towing vehicle and the loaded trailer (including all cargo and passengers) that the power train can handle without risking costly damage. The measured GCW must never exceed the GCWR. (Important: The towing vehicle's brake system is rated for safe operation at the GVWR -- not GCWR. Separate functional brake systems should be used for safe control of towed vehicles and for trailers weighing more than 1,500 lbs. when loaded).
Gross Vehicle Weight (GVW) - Base Curb Weight plus actual Cargo Weight plus passengers. It is the actual weight that is obtained when the fully loaded vehicle is driven onto a scale.
Gross Vehicle Weight Rating (GVWR) - The maximum allowable weight of the fully loaded vehicle (Base Curb Weight plus options plus cargo plus passengers). The vehicle's measured GVW must never exceed the GVWR. The GVWR along with other maximum safe vehicle weights, as well as tire, rim size and inflation pressure are shown on the vehicle's Safety Compliance Certification Label, located on the left front door lock facing or the door latch post pillar.
Maximum Loaded Trailer Weight - Is the highest possible weight of a fully loaded trailer the vehicle can tow. It assumes a towing vehicle with mandatory options, no cargo and the driver only (150 lbs.). The weight of additional optional equipment, passengers, cargo and hitch must be deducted from this weight.
For fifth wheel towing, the maximum allowable trailer weight is the GCWR minus the actual tow vehicle weight. If stated in a brochure, it will be the GCWR minus the Base Curb Weight and 150 lbs for a driver. It is an idealized maximum and not a "real world" capacity. The weight of additional optional equipment, passengers, cargo and hitch must be deducted from this weight.
Payload - Combined, maximum allowable weight of cargo and passengers that the vehicle is designed to carry. It is Gross Vehicle Weight Rating minus the Base Curb Weight.
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