M+S or Winter tires required in western U.S.?
I did a search of DOT websites. It appears M+S or winter (mountain-snowflake marked) tires are not required in WA, ID, MT, UT, CA, NV, AZ unless conditions warrant authorities to require them i.e....
Forum Discussion
If your vehicle is over 10,000 and chain up lights are on, you must chain up. In Washington, you must carry chains from Oct date through to April date.
WSDOT winter driving
WSDOT winter driving
