Driving in snow and using chains over the passes

October 8, 2026

Every mountain pass in Washington is run by WSDOT, and in winter the signs at the bottom of the pass tell you what your car needs. The pass status for the trailhead you are driving to is in the Right now section of each trail's page, with a link to WSDOT's report.

The four signs

1. Traction tires advised. Oversized vehicles are prohibited. Snow is possible; a car with all-season tires is allowed but should carry chains.
2. Traction tires required. Chains required on vehicles over 10,000 pounds. Your tires must be traction tires (see below) or you must put chains on.
3. Chains required on all vehicles except all-wheel and four-wheel drive. Two-wheel-drive cars chain up here, no exceptions. AWD and 4WD may continue without chains if they have traction tires, and must still carry chains.
4. Chains required on all vehicles, no exceptions. Rare, and it means it is bad. Most people should wait or turn around.

WSDOT changes the sign as the road changes, sometimes several times a day. The level shown in this app is WSDOT's current one; it can be different by the time you reach the pass.

Traction tires

A traction tire is marked M+S (mud and snow) or with the mountain-and-snowflake symbol, with at least an eighth of an inch of tread. Most all-season tires carry the M+S mark; check the sidewall. Studded tires are legal in Washington from November 1 to March 31. Approved chains are also an acceptable alternative to traction tires.

Carry chains from November 1

From November 1 to March 31, WSDOT requires vehicles on the main pass routes to carry chains even when none of the signs are up: I-90 over Snoqualmie, US 2 over Stevens, US 97 over Blewett and US 12 over White, among others. If the chains do not fit your tires, they do not count; check the size before the first storm.

Putting them on

• Practice at home, once, on a dry driveway. Doing it the first time in the dark at 28 degrees with trucks going by is how people lose fingers and gloves.
• Use the chain-up areas. They are signed before each pass. Never stop in a lane or on the shoulder of the highway to chain up.
• Chains go on the drive wheels: front on a front-wheel-drive car, rear on rear-wheel drive. Your owner's manual says which, and some cars cannot take chains at all.
• Drive under 30 mph with chains on, and take them off as soon as you are back on bare pavement. Chains on dry road wreck the chains and the road.
• Carry a headlamp, gloves you can get wet, and something to kneel on. Keep them with the chains, not in the trunk under the gear.

Before you go

• Open the trail's page here and look at the pass line, the forecast at the trailhead and the snow level.
• Look at the WSDOT cameras on the same page; a picture of the road beats any forecast.
• Chinook (SR 410) and Cayuse (SR 123) close for the season, usually in November, and North Cascades (SR 20) closes with the first big snow. A closed pass is shown as a closure here; there is no chain option on a closed road.
• Leave early. Most pass trouble on a weekend happens in the afternoon when the road is busy and the snow is soft.

Chain and traction-tire rules are WSDOT's and can change; their mountain passes page has the current wording.