What is a traction tire?

The in basket: Don McGuirk of South Kitsap wonders what constitutes a “traction tire,” the requirement for crossing the mountain passes during snow storms that is one step down from being required to chain up.


The in basket: Don McGuirk of South Kitsap wonders what constitutes a “traction tire,” the requirement for crossing the mountain passes during snow storms that is one step down from being required to chain up.
“I don’t want to get up to the summit and have the State Patrol pull me over and say ‘Don’t move until we tell you to,'” he said. He has what are designated M&S (mud & snow) tires but he wasn’t sure that will suffice.
The out basket: Ah, the wonders of Google, the Internet search engine. I called it up and typed in “Traction tires” and in seconds, there was the Washington State Patrol’s “frequently asked questions” site on the subject, beginning with “What qualifies as a traction tire? Do mud and snow tires qualify?” 
The answer: Tires that are labeled snow tire, all-season, all-weather, or studded (must be labeled M&S on the sidewall) qualify so long as they meet the standards set in WAC 204-24-040 Traction Devices.
That WAC, for Washington Administrative Code, is impossibly complex and I must assume tire manufacturers comply with it. Two parts that might help a layman call for a tread depth of no less than 4/32 of an inch on a traction tire, and it says the sidewall notation doesn’t have to specifically be “M&S.” MS, M/S, M-S and other combinations of the two letters will work.
The 4/32 of an inch requirement is twice the 2/32 inch depth required of any tire under normal circumstances.

6 thoughts on “What is a traction tire?

  1. Don’t forget tire “siping” (Google that, as it is much easier than explaining it here!). It is considered a “traction tire” or “traction device”.

    Just spent some bucks for new tires last month, but did some research beforehand on “siping”, and decided to go for it (it’s legit, legal, and so I had the new tires and the “siping” done at Les Schwab in Poulsbo for a small, additional fee)…

    I’m very convinced I have MUCH better traction (even considering driving in the mess of this past weekend— my tires wouldn’t even spin very much– if at all– on the ice and compact snow!) And now I have a legal pass of “traction tires required” should I choose to drive over the mountains…

  2. Tire traction test data has shown empirically that peak skid number dry pavement traction performance of bias ply tires is inversely proportional to the dynamic instantaneous tire load and is a function of inflation pressure.

  3. Tractions tires are available for cars, trucks and SUVs. There is a wide range of traction tire styles depending on the desired use. The use of traction tires is mandatory in some circumstances.

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