Studded Tire Season and Chain Controls in Washington

The seasonal window sits in RCW 46.37.420(2). The section first bans any block, flange, cleat, or spike projecting beyond the tread, then carves out tire chains, alternative traction devices, and imbedded metal studs when they are needed because of snow, ice, or other skid conditions. It then closes the carve-out for part of the year: metal studs may not be used between April 1st and November 1st. Read literally, the last lawful day for studs is March 31 and they become lawful again on November 1. The same subsection gives the state Department of Transportation power to determine additional periods in which studded tires are lawful, which is why WSDOT and not the Legislature is the body that announces any extension in a late-snow spring.

Retractable studs are the exception that lets a vehicle stay equipped all year. Under RCW 46.37.420(2)(a) and (b), a vehicle may carry retractable studded tires year round if the studs retract pneumatically or mechanically to below the wear bar when not in use and are engaged only between November 1st and April 1st. Those studs may be metal or another material, and RCW 46.04.272(3) exempts them from the lightweight stud weight limits entirely.

For ordinary fixed studs, RCW 46.04.272 sets the weight ceiling by Tire Stud Manufacturing Institute size: no more than 1.5 grams at TSMI size 14 or less, no more than 2.3 grams at size 15 or 16, and no more than 3.0 grams at size 17 or larger. The stud must also be one the tire manufacturer recommends for that type and size of tire. Two companion sections push the limit onto the supply chain rather than onto the driver. RCW 46.37.4215 has required, since January 1, 2000, that anyone selling studs to a Washington tire dealer certify them as lightweight or retractable by clearly marking the shipping boxes or containers "lightweight," and RCW 46.37.4216 has, since July 1, 2001, barred the sale of a studded tire or of a stud for installation unless it qualifies as a lightweight or retractable stud.

The State Patrol installation standards are in WAC 204-24-030 and are unusually specific. Studs must be metal tipped with tungsten carbide. They may be inserted only into a new or newly recapped tire that has the pin-holes molded into the tread, never into a tire that has already been driven on a vehicle, and only by the tire manufacturer or by a tire dealer or jobber working to the manufacturer specifications. A tire sold or offered for sale as a studded tire must have at least seventy metal studs evenly spaced around the tread, and it must keep at least fifty-six studs at all times to still count as a studded tire or as an approved traction device. Subsection (6) bars metal studs outright on any vehicle of ten thousand pounds gross vehicle weight or over, with school buses and fire department equipment exempted by subsection (7) and separately authorized by RCW 46.37.420(4).

Chain control is the second and larger half of the Washington winter driving answer. RCW 47.36.250(1) lets WSDOT post three escalating levels: traction advisory with oversize vehicles prohibited; the same plus chains required on vehicles over 10,000 GVW; and the same plus chains required on all vehicles except all wheel drive. Subsection (3) says those signs may never prohibit studded tires from November 1st to April 1st, but that when the department determines chains are required and no other traction equipment will suffice, the requirement applies to all types of tires including studded tires. Studs are therefore protected from being signed away, and are not a substitute for chains once chains are posted.

WAC 204-24-050(1) makes it unlawful for a vehicle under 10,000 pounds to enter a posted control area without the specified device mounted on its drive tires. All wheel drive vehicles are excused from a chains required sign if all wheels are in gear and fitted with approved traction devices, but only if tire chains for at least one set of drive tires are carried in the vehicle. WAC 204-24-040(3) defines an approved traction tire as one with at least 4/32 inch of tread measured at three points around the circumference, an aggressive pattern whose rib, lug, block or button edges sit at an angle greater than thirty degrees to the circumferential centerline, shoulder lugs protruding at least half an inch on at least one side of the tread, and a sidewall permanently marked mud and snow, an M and S contraction, or the mountain and snowflake symbol.

Trucks face a carry requirement rather than only a use requirement. WAC 204-24-050(2)(i) obliges every vehicle or combination over 10,000 pounds GVWR to carry enough chains from November 1 to April 1 on twelve named corridors, among them I-90 between North Bend at milepost 32 and Ellensburg at milepost 101, SR-2 between Dryden and Index, SR-410 from Enumclaw to Naches, SR-12 between Packwood and Naches, SR-542 on the Mount Baker highway, SR-970, and both the Tonasket to Kettle Falls and Newhalem to Winthrop stretches of SR-20. Vehicles making local deliveries shown on their bills of lading and not crossing the pass are exempt while outside a chain required area. Those trucks must also carry a minimum of two extra chains, automatic chains do not excuse carrying regular chains for the outside drive tires, and plastic chains are not allowed at all.

Using studs outside the season, or fitting studs that fail the State Patrol standards, is a traffic infraction. 2 rather than from a figure printed in the statute. 010(6), which is how a tire shop installing non-conforming studs is reached. 63 RCW subject to a penalty of five hundred dollars including all statutory assessments. WSDOT or the State Patrol may also simply turn a vehicle back, because WAC 204-24-050(4) lets either agency prohibit a vehicle from entering a chain or approved traction device control area when it determines the vehicle will experience difficulty traveling the area safely. O. 440 for failing to appear.