South Dakota Studded Tires: Legal October 1 to April 30, Banned May 1 to September 30

The base rule in South Dakota is not the stud statute but SDCL 32-19-2, which bans any block, stud, flange, cleat, spike, or other protuberance of a material other than rubber that projects beyond the tread of the traction surface. That section carves out farm machinery whose protuberances will not injure the highway, and tire chains of reasonable proportions when snow, ice, or other skid conditions require them. A violation of 32-19-2 is a petty offense, which South Dakota treats as a civil action under SDCL 22-6-7 with a twenty-five dollar judgment set by SDCL 23-1A-22.

SDCL 32-19-3 then lifts that ban for metal studs, and it does so by naming the months when driving on them is forbidden rather than the months when they are allowed. The prohibited period runs from May first to September thirtieth of each year; the permitted period runs from October first to April thirtieth. The section opens with a notwithstanding clause reaching 32-19-2 and also the axle weight and tire width sections at SDCL 32-22-21 and 32-22-22, so a studded tire that satisfies 32-19-3 is not separately exposed under those provisions. Two vehicle types escape the calendar entirely: a school bus, and a fire-fighting vehicle with a gross vehicle weight of over five thousand pounds owned or operated by any unit of local government. Both may run metal studs at any time of year. Driving on studs in the closed season is a Class 2 misdemeanor, punishable under SDCL 22-6-2(2) by up to thirty days in a county jail, a fine of up to five hundred dollars, or both.

SDCL 32-19-3.2, added by SL 2008, ch 159, is the provision that catches drivers who assume the tire itself is the offense. It allows a vehicle fitted with retractable studs to be used at any time of the year on South Dakota highways, but forbids engaging or extending the block, stud, flange, cleat, spike or other protuberance from May first to September thirtieth, inclusive. The offense is therefore deploying the stud, not owning the tire, and it too is a Class 2 misdemeanor.

The winter side of the chapter also gives the state a power most drivers never see used. Under SDCL 32-19-3.1, enacted in 1986, the secretary of transportation may restrict public travel on the state trunk highway system to four-wheel drive vehicles or to vehicles equipped with tire chains, studded snow tires, or snow tires whose tread is of sufficient abrasive or skid-resistant design, composition and depth for icy or snow-packed roads. The restriction only binds if signs of substantial construction are placed at the beginning, the end and major points of intersection of the affected stretch. Driving a non-conforming vehicle past those signs is a Class 2 misdemeanor.

Separately, SDCL 32-19-13 sets the tread floor that applies to studded and unstudded tires alike: no licensed motor vehicle may run a tire cut into the fabric, worn so the fabric shows, knotted or bulging in the sidewall or tread, or with less than two thirty-seconds of an inch of tread on any two adjacent grooves. Front-axle tires on a vehicle of ten passenger or more capacity, or exceeding twenty-six thousand pounds gross weight, must carry at least three thirty-seconds.

Roadside enforcement is by the Division of Highway Patrol under SDCL chapter 32-2 and by county and municipal officers. 2 is charged as a Class 2 misdemeanor, which SDCL 22-6-2(2) caps at thirty days in a county jail or a five hundred dollar fine or both, and that section also requires the sentencing court to order restitution to any victim under chapter 23A-28. The older cleat and protuberance offense in SDCL 32-19-2 is only a petty offense, so it proceeds as a civil action in which the state is plaintiff under SDCL 22-6-7 and chapter 23-1A, and a prevailing state recovers a twenty-five dollar judgment under SDCL 23-1A-22 that the trial court may reduce or eliminate in the interest of justice.

Local authorities cannot set their own dates: SDCL 32-14-3 bars them from enacting or enforcing any rule or regulation contrary to chapters 32-14 to 32-19, and the stud sections sit in chapter 32-19. There is no annual lane to catch a stud in the off season: SDCL 32-21-4 to 32-21-26 were repealed by SL 1979, ch 220, § 8, so a Highway Patrol officer acts under SDCL 32-21-28, which allows a stop and inspection of the vehicle, its equipment, license plates and registration on evidence of nonconformance with chapters 32-14 to 32-19, and may instead issue a warning ticket under SDCL 32-21-29 requiring correction within ten days.