Useful Definitions

Booster Axle
A unit comprising a frame, suspension system, and axles attached to the rear of a vehicle by a coupling device that transmits load to the unit’s axles. The coupling device may pivot to allow the unit to trail the vehicle through turns. If the coupling device does not pivot, the unit must have selfsteering axles. Booster axles are not titled or licensed in South Dakota.

Commercial Vehicle
A motor vehicle used to transport persons or property for hire, for interstate service or transportation, compensation, or profit. See Vehicle Registration (page 11), Commercial Motor Vehicle Definition (page 68), and CDL Classifications, Endorsements, Restrictions & Exemptions (page 72).

Divisible Loads
Loads that can be reduced to legal weight and dimensions within an 8-hour period.

Gross Combination Weight Rating (GCWR)
The value specified by the manufacturer as the loaded weight of a combination (articulated) motor vehicle. In the absence of a value specified by the manufacturer, GCWR is determined by adding the GVWR of the power unit and the actual total weight of the towed unit and load.

Gross Vehicle Weight (GVW)
The actual gross weight of the vehicle or vehicle combination, including the load.

Gross Vehicle Weight Rating (GVWR)
The value specified by the manufacturer as the maximum loaded weight of a single motor vehicle.

Interstate Commerce
Trade, traffic, or transportation:

  • between a place in a State and a place outside of that State or outside the United States;
  • between two places in a State through another State or through a place outside of the United States; or
  • between two places in a State as part of trade, traffic, or transportation originating or terminating outside of the State or the United States.

Interstate Highway System
The Dwight D. Eisenhower National System of Interstate and Defense Highways—in South Dakota, I-29, I-90, I-190, I-229.

Intrastate Operation
Vehicle movement entirely within a single State.

Single Axle
One or more consecutive axles spaced within 40 inches or less.

State Highway System
All highways, except those on the Interstate Highway System, administered and maintained by the South Dakota Department of Transportation.

State Trunk Highway System
All highways administered and maintained by the South Dakota Department of Transportation, including SD, US, and Interstate highways.

Steering Axle
Any axle at the front of a motor vehicle that is activated by the operator to steer the vehicle.

Tandem Axle
Two or more consecutive axles spaced more than 40 inches but not more than 96 inches apart.