Where can I find out about studded tires, traction tires, traction devices, etc?

The Washington State Patrol (WSP) regulates vehicle equipment including tires. Studded tires are approved for use from Nov. 1 to March 31. The Washington State Department of Transportation (WSDOT) determines additional periods in which they can be used. Both WSDOT and the WSP have good information at: • WSP - Traction Devices (includes links to the state laws and regulations) • For information on traction devices, tires and chains for commercial vehicles (trucks over 10,000 lbs. GVW), contact the WSDOT Motor Carrier Services Office at 1-800-562-6902, or visit the nearest WSDOT Permit Office.  more