Truck and trailer rules in North Dakota: licence classes, trailer brakes, size and weight limits
What the North Dakota Century Code says about Class A and Class B licences above 26,000 pounds, brakes or safety chains on trailers, safety chains between vehicles, the 8 foot 6 inch width, 14 foot height and length limits, and gross and axle weight on and off the interstate.
Checked against the sources at the bottom of this page on October 9, 2026. Rules, fees and pay change: the source has the last word.
This page reports what the official source says. It is not legal advice: ask the office named here. The sources are three chapters of Title 39, Motor Vehicles, of the North Dakota Century Code, published by the North Dakota Legislative Branch: chapter 39-06.2 on commercial driver's licenses, chapter 39-21 on equipment of vehicles and chapter 39-12 on size, width and height restrictions. Federal background and the other places are on the parent page, trucks and trailers for tree work.
At a glance
| Item | What the sources say |
|---|---|
| Commercial motor vehicle | Combination rated 26,001 pounds or more with a towed unit over 10,000 pounds; single vehicle over 26,000 pounds; 16 or more passengers; placarded hazardous materials |
| Class A | Combination rated over 26,000 pounds where the towed vehicle is rated over 10,000 pounds |
| Class B | Single vehicle rated over 26,000 pounds, towing a vehicle not over 10,000 pounds |
| Trailer brakes | Safety chains or brakes on a trailer or semitrailer above 25 miles per hour; brakes applied from the cab and automatic on breakaway |
| Safety chains | Required between towing and towed vehicles, except at a fifth-wheel coupling |
| Width, height | 8 feet 6 inches wide; 14 feet high |
| Length | 50 feet single unit; 75 feet for a two-unit combination; 53 feet trailer or semitrailer |
| Weight | 80,000 pounds gross on the interstate; 20,000 pounds single axle |
The commercial vehicle line and licence classes
Section 39-06.2-02 defines a commercial motor vehicle as a motor vehicle or combination designed or used to carry passengers or property in one of four cases. The first is a combination with a gross combination weight rating or weight of 26,001 pounds or more, provided the towed unit is rated or weighs more than 10,000 pounds. The second is a vehicle with a gross vehicle weight rating or weight of more than 26,000 pounds. The third is a vehicle designed for 16 or more passengers including the driver. The fourth is a vehicle carrying hazardous materials that must be placarded under 49 CFR part 172, subpart F.
Section 39-06.2-09 sets the classes. A class A licence covers any combination with a gross vehicle weight rating of more than 26,000 pounds if the rating of the vehicles being towed is more than 10,000 pounds. A class B licence covers a single vehicle rated more than 26,000 pounds, and that vehicle towing a vehicle of not more than 10,000 pounds. A class C licence covers a single vehicle rated 26,000 pounds or less, or that vehicle towing a vehicle rated not more than 10,000 pounds, when the vehicle is built for 16 or more passengers or carries placarded hazardous materials. The same section bars a class A, B or C licence from anyone under 18, apart from a licence specially restricted for custom harvesting. See chapter 39-06.2 on commercial driver's licenses.
Trailer brakes and safety chains
Section 39-21-32 requires every motor vehicle other than a motorcycle to have brakes able to control, stop and hold it, with two separate means of applying them, each effective on at least two wheels. For trailers, it says every trailer or semitrailer operated above 25 miles per hour must have safety chains or brakes adequate to control, stop and hold it. Those brakes must be designed to be applied by the driver of the towing vehicle from its cab, and connected so that on an accidental breakaway of the towed vehicle they apply automatically. The section sets no trailer weight line. It also requires parking brakes able to hold the vehicle on any grade where it is operated, and section 39-21-33 says all brakes must be kept in good working order and adjusted to work as equally as practicable on opposite sides.
Section 39-21-44.2 says the drawbar or other coupling between vehicles, when one tows the other on a highway, must include safety chains connecting them. The coupling and chains must be designed and built to prevent the vehicles from uncoupling unintentionally. The chain requirement does not apply to a fifth-wheel coupling, or to a vehicle towing an implement of husbandry (or the reverse) at no more than 25 miles per hour. See chapter 39-21 on equipment of vehicles.
Width, height and length
Section 39-12-04 limits a vehicle with its load to 8 feet 6 inches in width and 14 feet in height, loaded or unloaded. The width limit has listed exceptions, including construction and building contractors' equipment, and the vehicles that move it, up to 10 feet wide when moved by contractors or resident carriers. Non-load-carrying safety appurtenances that stick out no more than 3 inches from each side of a trailer are left out of the trailer width. The height limit does not cut back any bridge or underpass lower than 14 feet.
The same section sets length limits that include the load. A single unit with two or more axles may not exceed 50 feet. A two-unit combination may not exceed 75 feet, and a three or four unit combination also 75 feet subject to director rules. A two, three or four unit combination may reach 110 feet on four-lane divided highways and highways the director and local authorities designate. A trailer or semitrailer may not exceed 53 feet, except that trailers and semitrailers titled and registered in North Dakota before July 1, 1987, and towed vehicles, may not exceed 60 feet. Length limits do not apply to building moving equipment, emergency tow trucks taking a disabled lawful combination to a nearby repair facility, or structural material of telephone, power and telegraph companies, among other listed cases. See chapter 39-12 on size, width and height restrictions.
Weight
Section 39-12-05 covers the interstate system. It limits a single axle to 20,000 pounds and a wheel load to 10,000 pounds, and a wheel to 550 pounds for each inch of tire width. Axles spaced over 40 inches and under 8 feet apart may carry 17,000 pounds per axle. Gross weight is set by a formula based on the distance between the extreme axles and the number of axles, and may not exceed 80,000 pounds. Section 39-12-05.2 allows more on the interstate only if Congress authorizes it.
Section 39-12-05.3 covers highways other than the interstate. It keeps the 20,000 pound single axle and 10,000 pound wheel load limits. For axles spaced over 40 inches and under 8 feet apart it allows 19,000 pounds per axle, 34,000 pounds on a tandem axle and 48,000 pounds on any group of three or more axles. Gross weight is again set by formula. It may not exceed 105,500 pounds on state highways unless otherwise posted, and 80,000 pounds on all other highways unless local authorities designate them up to 105,500 pounds. The section also describes permits above those figures, including one for trucks up to 129,000 pounds at US$100 per month or US$700 annually, as the Century Code states the fee. Section 39-12-02 covers special permits for oversize and overweight vehicles.
Sources
- North Dakota Legislative Branch, North Dakota Century Code chapter 39-06.2 commercial driver's licenses, read October 9, 2026
- North Dakota Legislative Branch, North Dakota Century Code chapter 39-21 equipment of vehicles, read October 9, 2026
- North Dakota Legislative Branch, North Dakota Century Code chapter 39-12 size, width and height restrictions, read October 9, 2026