Utah Studded Tires: Tungsten Carbide Only, October 15 to March 31, .050-Inch Projection Cap

Utah writes the studded-tire allowance as an exception rather than as a permission. Subsection (3) of Utah Code 41-6a-1636 states the flat rule: a person may not have a tire on a vehicle moved on a highway that carries on the tire's periphery a block, stud, flange, cleat or spike, or any other protuberance of any material other than rubber that projects beyond the tread of the traction surface. Everything a Utah driver may lawfully run in winter is an exception to that sentence, which is why the material of the stud matters as much as the calendar.

The material is named. Subsection (5)(a) permits protuberances consisting of tungsten carbide studs and nothing else. A steel-stud or ceramic-stud tire is not covered by the carve-out and remains prohibited under Subsection (3) even in January. The projection limit is .050 inches measured beyond the tread of the traction surface, so a worn tire whose tread has receded around a fixed stud can drift out of compliance without the stud itself changing.

The window is written as two periods, not one. The statute allows the studs to be used only during the winter periods of October 15 through December 31 and January 1 through March 31 of each year. In practice that is a continuous October 15 to March 31 season, but the drafting splits at the calendar year, and there is no grace period at either end and no weather trigger: April 1 is unlawful in St. George and in Logan alike, whatever the forecast on the Bear River Range says.

Weight is the third condition. Under Subsection (5)(a)(iii) studs may not be used on a vehicle with a maximum gross vehicle weight rating in excess of 9,000 pounds unless the vehicle is an emergency vehicle or a school bus. That reaches heavier three-quarter-ton and one-ton pickups and most box trucks, so a Utah contractor's truck can be over the line while the same studded tire is legal on the family car beside it.

Utah keeps chains in a different subsection with different conditions. Subsection (5)(c) allows tire chains of reasonable proportions when required for safety because of snow, ice or other conditions tending to cause a vehicle to skid. Chains carry no calendar window and no GVWR ceiling, because they are condition triggered rather than season triggered. Whether chains or other traction devices are required on a given road is a separate question governed by the Utah Department of Transportation's traction rule, Utah Administrative Code R920-6, and UDOT's own guidance states that UDOT or law enforcement agencies determine when road conditions require traction devices and that travelers are notified by road signs, message boards, the UDOT traffic app and UDOT social media. UDOT does not publish a stud season of its own; the October 15 to March 31 dates exist only in Section 41-6a-1636.

There is a rulemaking door that has not changed the answer. Subsection (4) lets the Department of Transportation make rules under the Utah Administrative Rulemaking Act permitting non-rubber protuberances if the department concludes they do not damage the highway significantly or constitute a hazard to life, health or property. Subsection (6) separately lets a highway authority issue special permits for farm tractors, other farm machinery, and traction engines or tractors with movable tracks having transverse corrugations. Neither route extends the passenger-car stud season.

Selling the wrong tire is its own offence. Utah Code 41-6a-1619(1) forbids selling or offering for sale equipment that does not comply with the standards adopted under Section 41-6a-1601, and it names the studded tire in the list alongside lamps, hydraulic brake fluid, seat belts, safety glass and motorcycle helmets. A Utah tire shop is therefore exposed on the sale, not only the driver on the road.

One more Utah figure sits in the same section and catches more drivers than the stud rule does. Subsection (7)(a) makes it unlawful to operate a vehicle with a tire in unsafe operating condition or with tread depth less than 2/32 inch measured in any two adjacent grooves at three equally spaced intervals around the circumference, and Subsection (7)(b) says the measurement may not be taken at a tread wear indicator, tie bar, hump or fillet. Subsection (8) bars a tire seller from selling a tire that fails Subsection (7).

A violation of any part of Section 41-6a-1636, including running studs outside the October 15 to March 31 window, running studs that are not tungsten carbide, exceeding the .050-inch projection, or studding a vehicle rated over 9,000 pounds GVWR that is not an emergency vehicle or school bus, is an infraction under Subsection (9). Utah has no periodic safety inspection lane for ordinary passenger cars, so enforcement is roadside by a peace officer under the Traffic Code. A tire retailer that sells or offers a non-complying studded tire faces separate exposure under Utah Code 41-6a-1619(1), and a retailer selling a tire below the 2/32 inch tread floor violates Subsection (8) of Section 41-6a-1636. Requirements to fit chains or other traction devices on a particular canyon road are enforced separately by UDOT and law enforcement under Utah Administrative Code R920-6 and are signed at the roadside.