Studded Tires in North Carolina: No Seasonal Window, 1/16-Inch Limit

The whole answer lives in one subsection. G.S. 20-122(b) opens with a flat ban: no tire moved on a highway may carry on its periphery "any block, stud, flange, cleat or spike or any other protuberance of any material other than rubber which projects beyond the tread of the traction surface of the tire." It then carves out three exceptions, and the studded snow tire is the third. The only number in the exception is one sixteenth of an inch, and the only test condition is "when compressed," meaning the stud is measured pressed into the tire the way it sits under the weight of the vehicle, not standing proud on an unloaded wheel.

What North Carolina does not have is a season. A full-text read of Chapter 20 of the General Statutes turns up the word "studs" exactly once, here in 20-122(b), and the word "stud" once more in the same subsection's list of banned protuberances. There is no October-to-April window of the sort other states impose, no removal deadline, and no authority anywhere in the Motor Vehicle Act for the Department of Transportation to declare one. The section is written statewide and names no county, no elevation and no date, so the rule that applies on a mountain street in the Blue Ridge is the same rule that applies in Wilmington in August.

The two neighbouring exceptions matter for winter driving. Farm machinery may run tires with protuberances "which will not injure the highway." Tire chains are permissible "of reasonable proportions upon any vehicle when required for safety because of snow, ice or other conditions tending to cause a vehicle to slide or skid." Note the direction of that clause: it is a permission, not a mandate. Nothing in 20-122 lets the state order chains onto vehicles or close a road to unchained traffic. The only permit power in the section is subsection (c), which lets the Department of Transportation or local authorities issue special permits for traction engines and tractors with movable tracks with transverse corrugation, and for farm tractors and other farm machinery.

Subsection (a) sets the baseline the stud rule qualifies: no vehicle may move on a public highway unless it has tires of rubber or other resilient material that depend on compressed air for support of a load, except by special permission of the Department of Transportation granted on a showing of necessity. Farm vehicles are excluded from that subsection entirely, and subsection (d) adds that driving farm tractors on dirt roads from farm to farm is not unlawful provided they neither damage the road nor interfere with traffic.

One enforcement point often gets this backwards. North Carolina still runs an annual safety inspection, and tires are on the inspected list, but G.S. 20-183.3(a)(7) sends the inspector to G.S. 20-122.1, not to 20-122. What the station checks is condition and wear: a tire is unsafe if it is cut, cracked or worn so as to expose tire cord, if there is visible tread separation or chunking, or if tread depth falls below two thirty-seconds of an inch at two or more locations around the circumference in two adjacent major tread grooves. Studs are not an inspection item at all. The one sixteenth of an inch limit is a roadside matter for a law enforcement officer, which is why a set of aggressive aftermarket studs can pass inspection every year and still draw a citation on the shoulder of US 421.

The section is old and settled. Its history line runs from 1937, c. 407, s. 85 through 1957, 1965, 1973, 1977 and finally 1979, c. 515. The General Assembly has not touched North Carolina's tire equipment rule in more than four decades, which is a fair signal that the year-round allowance is deliberate rather than an oversight waiting to be corrected.

S. 20-122 sits in Part 9 of Article 3 of Chapter 20, the size, weight, construction and equipment part. That placement decides the penalty. S. 20-176(a) provides that a violation of a provision of Part 9, 10, 10A or 11 of the Article is an infraction unless the violation is specifically declared by law to be a misdemeanor or a felony, and 20-122 declares nothing of the kind, so an over-limit stud is a noncriminal infraction. S. 20-176(b) caps the penalty at one hundred dollars unless a specific penalty is provided elsewhere, and none is.

S. 1(a) an infraction cannot be punished by imprisonment, and the proceeds of the penalty go to the county in which the infraction occurred for the use of the public schools. S. 3. Disposition follows Article 66 of Chapter 15A. S. 20-176(d) adds a civil consequence that outlasts the citation: for deciding whether a Chapter 20 violation is negligence per se, crimes and infractions are treated identically, so an over-limit stud that contributes to a collision can be used against the driver in a damages suit.