Classifying Medium and Heavy-duty Trucks

heavy duty truck in a parking lot

Categorizing Big Trucks

When you think of medium- and heavy-duty trucks, what comes to mind? While some may think solely of equipment like tractor trailers, flatbeds and refrigerated units, there are actually a wide range of vehicle types in these categories — from boom trucks and dump trucks to semis and garbage trucks. We’ll cover details on how these big trucks are classified and why it’s important to know the correct classification.

How are vehicles classified? 

To classify vehicles, the U.S. Department of Transportation (USDOT) categorizes them based on gross vehicle weight ratings (GVWR) — which is a safety standard used to prevent overloading. It’s designed to limit the maximum weight of a vehicle including fuel, passengers and freight. Basically, the manufacturer (Original Equipment Manufacturer, or OEM) determines the maximum acceptable weight of the vehicle based on things like axle strength, brake efficiency, tire capability and the vehicle’s frame.

Exceeding a truck’s GVWR can cause safety concerns such as brake failure, tire strain, ineffective suspension components and other issues, so it is important for all carriers and drivers to understand the limits.

Vehicle classes

Officially, the USDOT categorizes vehicles into eight classes based on their GVWR. Classes one through three make up light-duty trucks, and medium and heavy-duty trucks are classes four through eight. On some charts, class nine may also be included for super heavy-duty trucks. Here’s how each truck class is broken down within medium- and heavy-duty truck categories:

Medium-duty trucks

Medium trucks weigh between 14,001 and 26,000 pounds and are typically used for transporting goods or people from city to city within the same state. Examples include box trucks, firetrucks and school buses. They are divided into the following three classes:

  • Class 4 — 14,001 to 16,000 pounds
  • Class 5 — 16,001 to 19,500 pounds
  • Class 6 — 19,501 to 26,000 pounds

Heavy-duty trucks

Any vehicle exceeding 26,001 pounds is considered heavy-duty. Examples include city transit buses, mobile cranes, cement mixers, refuse trucks, and tractors designed to pull refrigerated trailers, dry vans and other equipment. These types of vehicles are primarily used for long-haul transportation and are divided into three categories: 

  • Class 7 — 26,001 to 33,000 pounds
  • Class 8 — 33,001 or heavier
  • Class 9 — Vehicles exceeding 60,000 pounds (super-heavy/special-duty truck)

Why truck weight and classification matters

Understanding which class vehicle belongs in is critical for compliance, safety and upkeep needs. Certain laws and maintenance requirements may apply depending on weight, including:

License levels

Since 1992, professional drivers have been required to obtain and carry a commercial driver’s license (CDL) to operate vehicles weighing more than 10,001 pounds. Today, there are three classes of CDLs based on truck weight — class A, B and C. For more information, the Federal Motor Carrier Safety Administration (FMCSA) provides a detailed overview of CDL classifications and requirements.

Hours-of-service (HOS) laws

HOS regulations apply to any commercial driver operating a vehicle that weighs more than 10,001 pounds. However, there are some exemptions including emergency relief vehicles, tow trucks responding to a breakdown, and CMV drivers operating in Alaska. 

Weigh station guidelines

Medium and heavy-duty trucks are required to stop at weigh stations. Bypassing open stations can result in being pulled over by a DOT officer, and consequences may include a citation or being escorted back to the station for a more thorough inspection

Permit requirements

Heavy-duty trucks hauling oversized shipments require certain permits and signage for transportation. If proper certification isn’t provided, the driver may have to halt transit until they have the appropriate documents — which could lead to delayed deliveries.

DOT number regulations

GVWRs also dictate whether a DOT number is required for operation. Vehicles that exceed 10,001 pounds must have a DOT number labeled on at least two sides of the vehicle.

Maintenance needs

The type of vehicle also determines the maintenance and repairs that are needed. It is critical to communicate this information to the repair facility — whether roadside assistance or scheduling a regular checkup. Understand more about CMV maintenance by learning how FleetNet America® maintains medium and heavy-duty vehicles.


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