Washington Revised Code Title 47. Public Highways and Transportation § 47.36.250. Dangerous road conditions requiring special tires, chains, or traction equipment--Signs or devices--Penalty

(1) If the department or its delegate determines at any time for any part of the public highway system that the unsafe conditions of the roadway require particular tires, tire chains, or traction equipment in addition to or beyond the ordinary pneumatic rubber tires, the department may establish the following recommendations or requirements with respect to the use of such equipment for all persons using such public highway:

(2) Any equipment that may be required by this section shall be approved by the state patrol as authorized under RCW 46.37.420.

(3) The department shall place and maintain signs and other traffic control devices on the public highways that indicate the tire, tire chain, or traction equipment recommendation or requirement determined under this section. Such signs or traffic control devices shall in no event prohibit the use of studded tires from November 1st to April 1st, but when the department determines that chains are required and that no other traction equipment will suffice, the requirement is applicable to all types of tires including studded tires. The Washington state patrol or the department may specify different recommendations or requirements for four wheel drive vehicles in gear.

(4) Failure to obey a requirement indicated under this section is a traffic infraction under chapter 46.63 RCW subject to a penalty of five hundred dollars including all statutory assessments.