Gross combined weight rating (GCWR) and what it means for trailer towing

From an NTEA member As a truck equipment upfitter, we are often asked to add trailer hitches and other trailer towing devices to the trucks we build for customers. How can we determine proper trailer hitch rating based on the need? Many companies experience this dilemma when balancing customers’ trailer towing wants with the performance capability of the selected truck chassis. GCWR (see definition at end of article) is a key factor in determining trailer towing ability and, subsequently, correct chassis hitch rating. OEMs decide GCWR based on a variety of factors, including specific drivetrain components, engine, transmission, number of drive axles, axle ratios and braking ability. Additionally, they test chassis towing and stopping performance before determining vehicle GCWR capabilities. Most chassis manufacturers provide trailer towing guides to help determine maximum GCWR based on vehicle configuration. These publications may have maximum trailer towing ratings based on conventional or fifth wheel towing. Alternatively, the truck dealer can help determine proper trailer tow rating using OEM order guide information or their application engineering department. The C in GCWR signifies that the combination of towing vehicle weight and towed vehicle (trailer) weight is included in the rating. Essentially, trailer towing capacity is equal to GCWR less the total weight of the towing vehicle, including payload (trailer tow rating = GCWR – weight of towing vehicle, including payload). When calculating towing vehicle weight, be sure to include the weight of the chassis, truck body, equipment, passengers, fuel and payload. Helpful examples To assist customers in selecting the appropriate capacity hitch, conduct a towing vehicle payload analysis, including all permanent equipment to be installed. This will aid in determining the towing vehicle’s fully equipped weight. Next, figure out normal payload for daily vehicle operation. For example, a truck has a 13,500-pound gross vehicle weight rating (GVWR), 25,500-pound GCWR, total weight for the towing vehicle with chassis of 6,100 pounds (including fuel), 2,800-pound body weight, 1,750-pound equipment weight (crane, welder, PTO, air compressor), 450-pound passenger weight (three seats at 150 pounds per seat) and 1,400-pound payload. This vehicle would have a maximum trailer capability of 13,000 pounds (25,500 pounds – 6,100 pounds – 2,800 pounds – 1,750 pounds – 450 pounds – 1,400 pounds = 13,000 pounds). If the payload were greater, the trailer towing capacity would be lower. Likewise, with decreased payload, there would be increased trailer towing capacity. A helpful method for determining maximum trailer towing capacity for a given vehicle, based on rated GCWR, is to calculate the base weight of the towing vehicle, including chassis weight, all body and equipment mounted on the chassis, and driver/passenger load. Using the previous example, maximum trailer tow rating would be the 25,500-pound GCWR, less the 6,100-pound chassis weight, less the 3,650-pound body and equipment weight, less the 150-pound driver weight — totaling 15,600 pounds. However, there may be other factors to consider when determining actual maximum towing capacity. It could be limited if the OEM specifies a maximum capacity based on type of towing (fifth wheel/gooseneck or conventional). Alternatively, if the chassis has a factory-installed conventional hitch rated for a maximum weight of 9,000 pounds — even though the truck has a higher towing capacity based on GCWR less the weight of the towing vehicle — maximum trailer towing capacity is limited by the 9,000-pound rated hitch. Using the previous example, a truck with a 25,500-pound GCWR, total weight of 9,900 pounds and maximum trailer tow capacity of 15,600 pounds, will require a hitch capable of towing at least 15,600 pounds if the customer wants to maximize vehicle towing capacity. If you have any questions, call NTEA’s Technical Services Department at 800-441-6832 from 8 a.m.–5 p.m. EST, Monday–Friday. GCWR definition As defined in NTEA’s Truck Equipment Handbook: GCWR Abbreviation for Gross Combination Weight Rating — Represents the entire weight of a vehicle at the ground with a trailer or trailers, including vehicle, equipment, driver, fuel and payload (everything that moves with the vehicle). The chassis drivetrain components, engine, transmission, axle and axle ratio are primary components in determining a vehicle’s GCWR, provided the proper towing devices are installed.

Gross combined weight rating (GCWR) and what it means for trailer towing

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