snow chains

We’re gonna need some bigger snow tires.

Photo courtesy WSDOT

You’re on one side of the mountains, and your holiday dinner—or ski vacation, or freshman dorm—is on the other. Mountain pass requirements can be confusing, so we spoke to Alice Fiman of the Communications office of the Washington Department of Transportation to get a primer for winter rules:

• First off, let’s appreciate that Snoqualmie Pass rarely closes because the weather is too cruddy. When it’s shut, says Fiman, it’s almost always for avalanche control (when you wouldn’t want to be there anyway) and to clear stranded cars and accidents.

• The lowest alert level you’ll see is "Traction Tires Advised," and the next is "Traction Tires Required." Don’t panic! "Most of what you call regular tires are traction tires, so most people have them on their cars," says Fiman. Whew! Check with an auto shop to confirm, but unless you’re street racing on extra-wides, you’ll probably good to go.

• When things get snowier and icier, the DOT moves up to "Chains Required." This is where it gets tricky; it really means that chains or four-wheel drive or all-wheel drive are required…though those with the latter two still have to have a set of chains in the trunk. It’s the law—yes, even for you people with Subarus. Oh, and "studded tires do not take the place of chains," notes Liman.

• At its worst, the road requirements will be raised to a more restrictive version of "Tire Chains Required," one that’s basically "Tire Chains Required for Everyone, Including You Rock Stars With Four- and All-Wheel Drive." It’s rare, something Liman has only seen a handful of times in her decade at the DOT. When it’s posted, even your kickass SUV may not be enough.

• You can find pass alerts online, on Twitter, or on lighted signs in the miles leading up to mountain passes. Oregon has similar policies and also has mountain cams to check conditions. In British Columbia, some routes require chains in your car from October to the end of April, so be sure to check the site. Drive carefully!