Truck and trailer rules in Oklahoma: licence classes, trailer brakes, stay chains, size and weight limits
What Title 47 of the Oklahoma Statutes says about commercial licence classes, brakes on trailers of 3,000 pounds or more, stay chains or cables, the 102 inch width, the 45 foot single truck length and the annual overload permit that names timber and chips.
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. All of the sources are sections of Title 47, Motor Vehicles, of the Oklahoma Statutes, published by the Oklahoma State Courts Network (OSCN). They cover driver licences in chapter 6, equipment in chapter 12 and size and weight in chapter 14. 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 licence | Class A, B or C commercial licence for the matching commercial motor vehicle; holder must be 18 or older; weight lines not on the pages read |
| Trailer brakes | Required on a trailer, semitrailer or pole trailer with a gross vehicle weight rating of 3,000 pounds or more; automatic on breakaway |
| Lighter trailers | No brakes needed below 3,000 pounds unless the towed weight exceeds 40 percent of the towing vehicle's rating |
| Stay chains | Every trailer or semitrailer other than a fifth wheel semitrailer is coupled with stay chains or cables |
| Width, height | 102 inches wide; 13 1/2 feet on a county road, 14 feet on a turnpike, interstate, U.S. or state highway |
| Length | 45 feet single truck; 70 feet for another combination, with listed exceptions |
| Weight | 20,000 pounds single axle; 34,000 pounds tandem; gross by the federal bridge formula |
| Carrier number | Not published on the pages read |
Licences
Section 6-101 says a person may not operate a motor vehicle on a highway without a valid Oklahoma driver licence for the class of vehicle. A person may not operate a Class A, B or C commercial motor vehicle unless the person is 18 or older and holds a valid commercial licence of that class. A Class A holder may operate motor vehicles in Classes A, B, C and D. A Class B holder may operate Classes B, C and D, and a Class C holder Classes C and D. The section also provides a restricted Class A or B commercial licence for harvest purposes and a commercial learner permit at 18. The pages read do not state the weight line for each class. See section 6-101 on class requirements.
Brakes and stay chains
Section 12-301 says every trailer, semitrailer and pole trailer with a gross vehicle weight rating of 3,000 pounds or more on a highway must have brakes adequate to control, stop and hold it, applied by the driver of the towing motor vehicle from the cab. Surge brakes are lawful on a trailer towing or carrying a vessel. The brakes must be connected so that they apply automatically on an accidental breakaway. A trailer rated under 3,000 pounds need not have brakes, but must have them if the weight of the towed vehicle exceeds 40 percent of the gross vehicle weight rating of the towing vehicle. See section 12-301 on brake equipment.
Section 14-106 says every trailer or semitrailer must have a coupling device that lets it follow in the path of the towing vehicle without whipping or swerving. Except for a semitrailer drawn by a truck-tractor designed to carry its front end, it must also be coupled with stay chains or cables to the drawing vehicle, of sufficient size and strength to prevent parting should the regular coupling break or disengage. Section 12-405.1 repeats the coupling device rule for trailers, semitrailers, manufactured homes and towed motor vehicles.
Width, height, length and weight
Section 14-103 sets the total outside width of a vehicle, with or without load, at 102 inches, leaving out tire bulge and approved safety devices. Height is limited to 13 1/2 feet on a county road and 14 feet on a turnpike, interstate, U.S. or state highway, unless a special permit allows more. No single truck may have an overall length, bumpers included, over 45 feet. No other combination of vehicles may exceed 70 feet on all roads and highways, apart from the exceptions the section lists, such as semitrailer lengths on the National Network. See section 14-103 on width, height and length.
Section 14-109 says no single axle weight may exceed 20,000 pounds on any road or highway, no set of tandem axles may carry more than 34,000 pounds, and the gross weight of a vehicle or combination may not exceed the value from the federal bridge formula in 23 U.S.C. section 127. Subsection D allows an annual special overload permit for vehicles carrying listed goods, including timber, pulpwood and chips in their natural state, if conditions in the subsection are met, among them registration at the maximum allowable rate. The same subsection sets the fee for that nontransferable annual permit, issued by the Department of Transportation, at US$350.
Sources
- Oklahoma State Courts Network, 47 O.S. section 6-101 class requirements for driver licenses, read October 9, 2026
- Oklahoma State Courts Network, 47 O.S. section 12-301 brake equipment required, read October 9, 2026
- Oklahoma State Courts Network, 47 O.S. section 12-405.1 coupling device for trailers, read October 9, 2026
- Oklahoma State Courts Network, 47 O.S. section 14-103 width, height and length of vehicle and load, read October 9, 2026
- Oklahoma State Courts Network, 47 O.S. section 14-106 trailers and towed vehicles, read October 9, 2026
- Oklahoma State Courts Network, 47 O.S. section 14-109 axle load limit and gross weight, read October 9, 2026