Will there be “snow in the valley” this year? As any longtime resident of our area knows, the answer is “who knows?” The only way to guarantee a snow encounter is to head to the mountains, which many of us will do one or more times this winter, for ski resorts, mountain retreats, snow parks, or points east of the Cascades.
Being prepared for winter driving is essential. It goes without saying that many an auto accident or stranding has been occasioned by snowy or icy roads. But in many areas, having your car properly outfitted for winter driving is more than just good sense- it's the law.
Most Southwest Washington residents heading into winter driving conditions are doing so in the Oregon Cascades. In Oregon, highway signs will tell drivers when chains or other traction devices are required on a stretch of road. Drivers can check ahead of time by going to https://tripcheck.com/Pages/Road-Conditions. If you're using tire chains, carry them with you in the vehicle at all times. For those not wanting to fuss with tire chains, traction tires may be used on vehicles rated at 10,000 lbs. gross vehicle weight (GVW) or less, and not being towed or towing anything. “Traction tires” are defined as studded tires, or ones specially designed for winter driving, which bear this logo:

Studded tires are legal in Oregon (and Washington) Nov. 1 through Mar. 31, but are discouraged due to the damage they cause to roadways. Failure to follow the rules means you might receive a citation, including for merely not carrying chains in your vehicle in a snow zone.
In Washington, if signs say chains are required, studded tires will not suffice to comply with the law, but having traction tires will bring you into compliance. You must still carry chains, even with traction tires, in the worst areas (usually mountain passes). Washington's winter driving requirements can be checked at https://www.wsdot.com/traffic/passes/.