Michigan Studded Tires: Banned in Practice by the 25% Wear Rule

The ban sits in two parts of section 710 of the Michigan Vehicle Code, 1949 PA 300. Subsection (a) bars metal or plastic track, and any tire equipped with metal that comes in contact with the surface of the road, on a public highway of this state. Subsection (b) bars the protuberance itself, naming a block, stud, flange, cleat or spike of a material other than rubber that projects beyond the tread of the traction surface. Both are written "except as provided in subsections (c), (d), and (e)," so the exceptions are a closed list. There is no general winter exemption, no exemption for four-wheel drive, and no exemption written for a vehicle registered in another state that drives into Michigan.

Subsection (c) is the one route an ordinary Michigan driver actually has. It permits a pneumatic tire in which wire of .075 inches in diameter or less is embedded, provided the tire is built so the percent of metal in contact with the highway does not exceed 5% of the total tire area touching the roadway. During the first 1,000 miles of use the allowance is looser, at 20% of the area, which accounts for the wire that wears away early in the tire's life. That describes a rubber-dominant winter tire with fine wire filaments, not the protruding carbide stud sold elsewhere as a studded snow tire.

Subsection (e) names the only people who may run actual ice grips or tire studs: a law enforcement officer operating a vehicle owned by a law enforcement agency, a person operating an ambulance, and a United States postal service rural carrier driving a vehicle the rural carrier owns and maintains as a prerequisite to employment in the postal service. A rural mail carrier in Alpena may therefore run studs on the car they bought themselves, while the neighbour driving the same road to work may not.

Subsection (d) directed the department of state highways and transportation to promulgate rules establishing acceptable standards to permit the use of a tire with studs on a street or highway after April 1, 1975, with separate provision for the extreme winter snow and ice conditions of the Upper Peninsula and the northern Lower Peninsula. Those rules exist as the Traction Devices rule set, R 247.171 to R 247.175, issued by the Bureau of Highway Technical Services. R 247.174 is the gate: "Studs or other traction devices shall not be used unless they wear either concrete or asphalt pavements, typical of those in this state, at a rate not to exceed 25% of the reference standard studded tire." R 247.171(1) fixes that yardstick as a size E 78-14, 4-ply bias construction tubeless snow tire carrying 90 Kennametal class III studs in six rows of fifteen, the tire used in a 1971 American Oil Company wear study, project 6128.

R 247.175 then supplies the calendar most drivers assume is the whole answer. A traction device permitted under the rules may be used only between November 15 and April 1 of the succeeding year, except in the Upper Peninsula and the northern Lower Peninsula, where the window runs October 1 to May 1. R 247.171(3) defines the northern Lower Peninsula as all counties whose southern boundaries are as far or farther north than the southern boundary of Missaukee county, a line that puts Traverse City, Gaylord and Alpena inside the longer window and Mount Pleasant outside it. The window is academic, though. The Michigan State Police state that to date no manufacturer of tire studs has supplied information to the Michigan Department of Transportation that their product meets or exceeds the required pavement wear specifications, so nothing on a tire shop shelf has cleared R 247.174 and the season never opens for it.

Two things Michigan does allow without argument. Subsection (b) preserves the right to use a tire chain of reasonable proportion upon a vehicle when required for safety because of snow, ice, or other condition tending to cause a vehicle to skid, with no calendar limit attached, and it preserves farm machinery running a protuberance which will not injure a highway. Note also R 247.172(2): the traction rules apply to all public streets and highways in this state and do not prevent the application of any other statute or local ordinance which is more restrictive, so a Michigan city may go further than the state rules but not the other way.

683. Subsection (2) of that section lets a police officer stop and inspect a motor vehicle on reasonable grounds shown and issue the driver a citation if a defect in equipment is found, and subsection (6) makes a violation of sections 683 to 711 with respect to equipment on vehicles a civil infraction rather than a crime. 00. 00 justice system assessment paid into the state justice system fund. 907(9) supplies the repair route: where a person has received a civil infraction citation for defective safety equipment on a vehicle under section 683, the court shall waive the civil fine, costs and assessments on receipt of certification by a law enforcement agency that repair of the defective equipment was made before the appearance date on the citation.

Tire sellers are reached separately. 710(g) forbids a person in the business of selling tires from selling or offering for sale for highway use a tire that is unsafe under subsection (h), which covers exposed belting material or cords, cord or tread separations, regrooved tires, tires marked "not for highway use" or "for racing purposes only", and tread worn to or below 2/32 inch on a passenger car, 1/32 inch on a motorcycle or moped, and 4/32 inch front on a vehicle weighing 10,000 pounds or more.