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The automotive industry is full of specialized terms and acronyms; it's easy to get overwhelmed by all of it! Whether you're a customer trying to understand the lingo, new to working in a dealership or just want a refresher, this crash course on chassis can help you better understand it all.

After Frame (AF)

Distance from the center of the rear axle(s) to the end of the frame.

Body Length (BL)

The distance from the foremost point of the body to the rearmost point of the body.

Cab to Axle (CA) // Cab to Tandem/Trunnion (CT)

Dimension from the back of the cab to the centerline of the axle or to the midpoint of the tandem (trunnion) axle. Clear CA or effective CA is the distance from the rear surface of any obstruction behind the cab to the center of the rear axle. If you have a tandem axle truck, then it is measured to the midpoint between the two rear axles. This measurement can help you determine the length of the body that can be mounted on the chassis.

Center of Gravity (CG)

The point at which the weight of the chassis, body and payload, if collectively or individually supported, would balance vertically, horizontally and laterally.

Chassis Cab (non-cutaway)

Incomplete vehicle with an occupant compartment that requires only the addition of cargo-carrying, work-performing or load-bearing components to perform its intended function.

Commercial Driver's License (CDL)

The vehicle’s GVWR is one of the factors that will effect whether the driver needs a CDL. If the truck has a GVWR, and GVW of 26,000 lbs. or lower, the driver does not need a CDL.

Class A license is required to operate any combination of vehicles with a gross combination weight rating of 26,001 lbs. or more. This includes towing a trailer weighing over 10,000 lbs. which makes the vehicle and trailer rating over 26,001 lbs.

Class B license is required to operate a single vehicle with a GVWR or 26,001 lbs. or more, and/or a vehicle with a GVWR of 26,001 lbs. or heavier that is towing another vehicle weighting up to 10,000 lbs.

Class C license is required if the vehicle you intend to drive does not meet the criteria for either Class A or B and it is meant to transport either: 16 or more passengers including the driver or hazardous material.


A chassis with no back wall on the cab to allow access from the cab to the attached body in the rear.

Frame Width (FW)

Overall width of the chassis frame measure behind the cab.

Gross Vehicle Weight (GVW)

This is the total weight of the truck, including all passengers, drivers, cargo, accessories, fuel, and fluid in the engine at any point in time. It is important that this measurement does not go over the GVWR, or it can be a safety hazard.

Gross Vehicle Weight Rating (GVWR)

This is the maximum total vehicle weight that is safe for the truck, established by the chassis manufacturer. The weight of the truck, any cargo, and passengers including the driver, as well as any fuel and fluid in the engine is included in the rating. Chassis manufacturers will most often set the GVWR lower than the combined axle ratings (the total amount of weight an individual axle can carry). This is due to the chassis manufacturer’s internal safety standards for durability, stability, and handling, as well as SAE International test protocols.

Gross Combined Weight Rating (GCWR)

Everything that moves with the vehicle is included in the GCWR. The weight of the truck, any cargo, passengers including the driver, any fluid or fuel in the truck, as well as the weight of the trailer and the trailer’s cargo is included. Exceeding the GCWR can cause a safety hazard.

Original Equipment Manufacturer (OEM)

In the automotive industry, it is the company that produces vehicles without any third-party components like bodies and equipment applied.

Pick-up Box Delete

Incomplete vehicle with the pick-up bed removed by the OEM.

Pick-up Box Removal

Completed vehicle with the pick-up bed removed by anyone other than the OEM.

Single Rear Wheel (SRW) / Dual Rear Wheels (DRW)

Single rear wheel is a single axle truck with single rear wheels. Single Rear wheels make for smoother driving without cargo, as well as easier driving in cities, suburbs, and highways. These trucks are more affordable to purchase outright, and have better fuel economy. A single rear wheel has less towing capability than a dual rear wheel, and less stability when towing in windy conditions.

Dual rear wheel is a single axle truck with dual rear wheels, also referred to as a dually. This feature is a must if you are towing large payloads, or driving through rough terrain. It adds stability to your truck which increases safety for your drivers and cargo. Having a dual rear wheel will allow the driver to safely get off the road in the case of a tire blowing out. Trucks with a dual rear wheel can be difficult to maneuver in cities, where parking and tight streets can be challenging. This feature can also reduce the truck’s mpg, especially in cities, and increase maintenance costs, because there are at least two extra tires to replace or rotate.

Two-Wheel Drive (2WD) // Four-Wheel Drive (4WD)

Two-wheel drive vehicles are either configured for front-wheel or rear-wheel drive, only sending power to two wheels.

Four-wheel drive vehicles use all four tires and are generally used in off-road applications.

Wheelbase (WB)

The wheelbase is the distance between the centers of the front and rear axles. When the truck has more than two axels, it is the distance between the steering axle and the center point of the driving axle group. This can affect body installation, weight distribution, and truck performance.