Wyoming Studded Tires: No Seasonal Window, but the Studs Must Be State Approved

Wyoming handles studs the way it handles tire chains, as a permanent exception to a general rule rather than as a seasonal privilege. W.S. 31-5-956(c) says no tire moved on a highway may carry on its periphery any protuberance of material other than rubber projecting beyond the tread, then permits three things: implements of husbandry with protuberances that will not injure the highway, tire chains of reasonable proportions when required for safety because of snow, ice or other skid conditions, and pneumatic tires having studs. Only the chain exception is tied to conditions. The stud exception is not, so a Wyoming driver who leaves studs on through July is not violating the statute.

The approval requirement is the part drivers miss. W.S. 31-5-956(c)(iii) ends with a flat sentence that pneumatic tires having studs must be approved by the superintendent. W.S. 31-5-935(a) separately directs the superintendent to adopt standards for studded tires alongside lamps, reflectors, hydraulic brake fluids, seat belts, safety glass, emergency disablement warning devices, motorcyclist helmets, eye protection devices and red rear bicycle reflectors, and W.S. 31-5-935(b) and (c) let those standards track United States Department of Transportation, Vehicle Equipment Safety Commission, American National Standards Institute or Society of Automotive Engineers specifications. W.S. 31-5-934(a) then puts the duty on the seller: a person shall not sell or offer for sale a studded tire until it has been approved by the superintendent. The compliance burden therefore sits with tire shops rather than with the motorist, but a home-fabricated stud pattern falls outside the exception.

W.S. 31-5-956(h) extends the whole tire section to motorcycles, motor-driven cycles, multipurpose vehicles, mopeds and off-road recreational vehicles under W.S. 31-1-101(a)(xv)(K)(II) that are registered under W.S. 31-2-232, so a studded motorcycle or a studded side-by-side plated for road use is governed by the same rule.

What Wyoming does regulate hard is winter travel itself. Under W.S. 31-5-956(e), when the superintendent or an authorized representative determines travel is sufficiently hazardous, highway travel may be restricted to vehicles using adequate snow tires or tire chains, all-wheel drive vehicles, or necessary emergency vehicles as defined in W.S. 31-5-102(a)(ii), including snow plows. In extremely hazardous conditions the restriction narrows to emergency vehicles and vehicles running chains, or to all-wheel drive vehicles on adequate snow tires carrying a mud and snow or all-weather rating from the manufacturer. The restriction takes effect when signs, including temporary or electronic signs, are erected on that portion of highway, and the operator of a commercial vehicle must then affix tire chains to at least two drive wheels at opposite ends of the same drive axle. W.S. 31-5-956(k) defines tire chains as two circular metal loops, one on each side of the tire, connected by not less than nine evenly spaced chains across the tread, or an equivalent traction device.

Tread depth is the other live number in the same section. W.S. 31-5-956(f) forbids operating on a tire in unsafe condition or below four thirty-seconds of an inch on the front wheels of a bus, truck or truck tractor and two thirty-seconds elsewhere, measured in two adjacent grooves at three equally spaced points around the tire and never at a wear indicator, tie bar, hump or fillet. No vehicle may run a tire with fabric showing through the tread or sidewall, and under W.S. 31-5-956(g) a tire seller may not sell a highway tire below two thirty-seconds.

Wyoming splits the penalties. S. S. 31-5-956(j): a misdemeanor with a fine of not more than $250, rising to not more than $750 where the violation causes an incident that closes all lanes in one or both directions of the highway. S. 31-5-1201, which makes any breach of the Wyoming traffic act a misdemeanor and sets a fine of not more than $200 for a first conviction, not more than $300 for a second conviction of the same offense within one year, and not more than $500 or six months in jail or both for a third or subsequent conviction within a year of the first. Prior convictions are introduced only after trial, for the purpose of setting the penalty. S. 31-5-956(e). S. 31-5-934(a) rather than the driver.