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Difficulty: MediumWeight Definitions and Limits (GVWR, GCWR, Axle Weights)

A commercial driver is preparing a two-axle straight truck for an interstate delivery. The vehicle has an empty (tare) weight of 12,400 lb12,400\text{ lb} and the following manufacturer specifications:

- Front steer axle Gross Axle Weight Rating (GAWR): 12,000 lb12,000\text{ lb}
- Rear drive axle Gross Axle Weight Rating (GAWR): 21,000 lb21,000\text{ lb}
- Gross Vehicle Weight Rating (GVWR): 31,000 lb31,000\text{ lb}

Under federal bridge and highway regulations, the maximum legal weight for any single axle on interstate highways is 20,000 lb20,000\text{ lb}. Assuming cargo is distributed across both axles without exceeding either individual limit, what is the maximum cargo payload weight (in pounds) that this vehicle can legally carry?

Answer: 18600 lb

Answer

The maximum allowable cargo payload is 18,600 lb18,600\text{ lb}.
To find the maximum allowable payload, the operating Gross Vehicle Weight (GVW) cannot exceed any statutory limit or manufacturer rating. The rear axle GAWR (21,000 lb21,000\text{ lb}) is capped by the federal single-axle statutory limit of 20,000 lb20,000\text{ lb}, giving a combined axle capability of 12,000 lb+20,000 lb=32,000 lb12,000\text{ lb} + 20,000\text{ lb} = 32,000\text{ lb}. However, the vehicle's GVWR is 31,000 lb31,000\text{ lb}, making 31,000 lb31,000\text{ lb} the governing maximum gross weight. Subtracting the unladen tare weight of 12,400 lb12,400\text{ lb} from 31,000 lb31,000\text{ lb} results in a maximum legal payload of 18,600 lb18,600\text{ lb}.

Step-by-Step Solution

1
Determine the effective weight limit for each individual axle by taking the lesser of the manufacturer GAWR and the federal single-axle statutory limit (20,000 lb20,000\text{ lb}).
Front steer axle limit is 12,000 lb12,000\text{ lb} and rear drive axle limit is min⁡(21,000 lb,20,000 lb)=20,000 lb\min(21,000\text{ lb}, 20,000\text{ lb}) = 20,000\text{ lb}.
A commercial motor vehicle must never exceed either the manufacturer's GAWR or the federal/state legal axle weight limit, whichever is lower.
2
Determine the maximum allowable Gross Vehicle Weight (GVW) by comparing the sum of legal axle limits against the vehicle GVWR.
Sum of axle limits = 12,000 lb+20,000 lb=32,000 lb12,000\text{ lb} + 20,000\text{ lb} = 32,000\text{ lb}. Vehicle GVWR = 31,000 lb31,000\text{ lb}. Maximum allowable GVW = min⁡(32,000 lb,31,000 lb)=31,000 lb\min(32,000\text{ lb}, 31,000\text{ lb}) = 31,000\text{ lb}.
The total laden weight of a single-unit vehicle cannot exceed its manufacturer GVWR even if the theoretical sum of its axles is higher.
3
Calculate the allowable cargo payload by subtracting the tare (unladen) weight from the maximum allowable GVW.
31,000 lb−12,400 lb=18,600 lb31,000\text{ lb} - 12,400\text{ lb} = 18,600\text{ lb}.
Payload capacity equals the maximum legal gross vehicle weight minus the empty weight of the truck.

Key Concept

Maximum allowable payload is governed by the lowest limiting factor among manufacturer GVWR, individual axle GAWRs, and statutory axle limits minus tare weight.
Estimated Time:1m 30s
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Topics

Weight Definitions and Limits (GVWR, GCWR, Axle Weights)

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