Wisconsin Studded Tire Ban and Its Four Narrow Exceptions

Section 347.45 is built as a general prohibition with a short list of escapes. Subsection (1) requires that automobiles, motor trucks, motor buses, truck tractors, trailers, semitrailers, recreational vehicles and mobile homes run on pneumatic tires and forbids any metal tire in contact with the roadway. Subsection (2) then reaches the tread itself: no vehicle, including farm tractors, implements of husbandry, animal-drawn vehicles and road machinery, may operate with any block, stud, flange, cleat, spike or other protuberance of a material other than rubber projecting beyond the traction surface. Three exceptions follow. Paragraph (a) covers farm tractors, implements of husbandry, bicycles, animal-drawn vehicles and road machinery running metal tires or protuberances that will not injure the highway. Paragraph (b) allows tire chains of reasonable proportions on any vehicle when required for safety because of snow, ice or other conditions tending to cause skidding. Paragraph (c) is the tire-design paragraph that contains the stud rule.

Paragraph (c) does two separate jobs, and Wisconsin drivers routinely conflate them. Its first half legalises a pneumatic tire with wire or wire coils embedded for traction on ice and snow, on a numeric design standard: after the first 1,000 miles of use the wire in contact with the roadway may not exceed 5 percent of the total tire area in contact with the roadway, and during those first 1,000 miles it may not exceed 20 percent. That is a permanent, year-round allowance available to everyone, and it is why studless winter tires and wire-reinforced traction tires raise no issue in Wisconsin. Its second half, the tungsten carbide stud provision, is the restrictive one, and it applies only to the four vehicle classes named in subd. 2. Studs on those vehicles may not project more than one-eighth inch beyond the tread surface under subd. 3.

The seasonal window is not in the statute. Subdivision 1. delegates it: the department shall, by rule, designate the times of year during which any tire described in the paragraph may be used. The Department of Transportation did that in one short chapter, ch. Trans 306, whose only section, Trans 306.01 (1), sets the period annually from the 15th day of November each year through the 1st day of April, both dates inclusive. The chapter carries a note stating plainly that the legislature has prohibited the general use of studded tires and pointing the reader back to s. 347.45. Trans 306.01 (2) adds one research route: studded tires for heavier vehicles, or for vehicles not specifically covered by statute, may be used for study only after written approval of the administrator.

The nonresident exception is narrower than visitors assume. It is written for an automobile that carries out-of-state registration and is in the course of passing through this state for a period of not more than 30 days. A studded car registered in Michigan, Minnesota or Illinois may cross Wisconsin inside the Trans 306.01 window. Someone who moves to Wisconsin and takes Wisconsin plates loses the exception the moment the registration changes, and there is no residency-based permit to replace it.

One escape valve exists outside all of this. Under s. 347.45 (3) the authority in charge of maintenance of the highway in question may, in its discretion, issue a special permit authorising operation on that highway of a vehicle whose operation the section would otherwise prohibit. That is a per-road permission from the county highway department, town, village or city that maintains the road, not a statewide waiver from the Department of Transportation.

What Wisconsin does enforce on winter tires is condition rather than studs. Section 347.45 cross-references s. Trans 305.30, which requires at least 2/32 inch of tread depth in every major tire groove measured at two points no less than 15 inches apart, forbids tires protruding more than 2 inches beyond the original fender line, and bars tires of different size or construction on the same axle except for a temporarily fitted spare.

A studded-tire violation is a non-criminal forfeiture. 50 (1) sets the range for violations of ss. 49, which includes s. 45, at not less than $10 nor more than $200, before court costs and the surcharges added to a Wisconsin uniform traffic citation. The offence is enforced roadside by a traffic officer; Wisconsin runs no periodic safety inspection of ordinary passenger cars at which studs would otherwise be caught. Exposure is not limited to the driver. 04 makes an owner who knowingly causes or permits an improperly equipped vehicle to be operated on a highway guilty of the same offence, and s.

03 makes it unlawful to sell for highway use any device, appliance, accessory or replacement part whose use on a motor vehicle is unlawful, which reaches a Wisconsin tire shop that mounts studs on an ordinary passenger car. The road authority that maintains the highway is also the body that may grant a special permit under s. 45 (3), so a contractor needing traction devices should approach it before fitting them rather than after a citation.