What's a traction tire?
The sign at the bottom of the pass says "Traction tires required". Do you have them? Here is how to check in two minutes, and what each sign means for your car.
Check your tires
1. Look at the side of the tire
Find one of these, usually in small letters near the size (like 215/60R16):
- M+S, M/S or "Mud and Snow". Most all-season tires have it.
- The mountain and snowflake: three peaks with a snowflake inside. Winter tires and some all-weather tires have it. It means the tire passed a snow test.
2. Check the tread
Push a quarter upside down into the groove in the middle of the tire. If you can see the top of Washington's head, the tread is under 1/8 inch (4/32), and in Washington it no longer counts as a traction tire. Worn tires slide on snow whatever the side says.
3. Know what drives your wheels
AWD or 4WD is on the back of many cars and in the owner's manual. It helps you get going, not stop: it is not a traction tire, and it doesn't replace one. If you use chains, they go on the wheels that drive the car (the front on most cars). On an AWD, the manual says which.
What the signs mean
Each state words its signs a little differently. On every pass page, Chains today turns the current sign into one answer for a car, an AWD or 4WD, and a vehicle that is towing or over 10,000 lb.
Washington
- Traction tires advised: nothing is required yet. Carry chains and slow down.
- Traction tires required: every vehicle needs traction tires, which in Washington means M+S or the mountain and snowflake, with at least 1/8 inch of tread. Studded tires count. If yours don't qualify, put chains on.
- Chains required on all vehicles except all-wheel drive: cars and trucks chain up. AWD and 4WD (in four-wheel drive) may go on with traction tires, and must carry chains.
- Chains required on all vehicles: everyone, AWD included. Studded tires don't replace chains.
Ignoring a chain sign is a $500 ticket in Washington. Studded tires are legal November 1 to March 31. WSDOT tires and chains
Oregon
In Oregon, "traction tires" means tires with the mountain and snowflake, or studded tires. M+S on its own is not enough.
- Carry chains or traction tires: you must have chains in the car, or traction tires on it.
- Chains required on vehicles towing or over 10,000 GVW: chains for trailers and big trucks. Everyone else carries chains or has traction tires.
- Chains required, traction tires allowed in place of chains: a car that isn't towing may use traction tires instead of chains. Towing or over 10,000 lb: chains.
- AWD and 4WD may skip chains when they weigh 6,500 lb or less unloaded, drive all four wheels, carry chains, have M+S, all-weather or traction tires on every wheel, and aren't towing. In the worst storms ODOT can still require chains on everyone.
Studded tires are legal November 1 to March 31. ODOT chain law
California
California posts three levels at chain control checkpoints, where crews check every car.
- R-1: chains, unless your car or light truck has snow tires (M+S) on at least the two wheels that drive it. Carry chains anyway. Towing: chains.
- R-2: chains on everything, except AWD and 4WD with snow tires on all four wheels. They must carry chains.
- R-3: chains on every vehicle, no exceptions. Usually the step before closing.
Chain installers at the checkpoints are independent businesses: agree on the price first and get a receipt. They can't sell or rent chains, so bring your own. Speed with chains: 25 or 30 mph. Caltrans chain controls
Chains, if you've never used them
- Buy them before the trip. The size is printed on the tire (like 215/60R16). Stores near the pass sell out, or charge more, on the first snowy weekend.
- Practice once at home, in dry weather, with gloves on. It is much harder the first time in the dark and slush.
- Put them on at the chain-up area, before the road looks bad. The rule starts where the sign is because the road can go from bare to ice within a mile, and a car that stops to chain up in a lane blocks everyone.
- Go slow with chains on (25 to 30 mph), and take them off at the chain-off area so they don't break on bare road.
Before you leave
- Look at the pass page for the report, the cameras and the forecast, then look again on the way.
- Full tank, warm clothes, gloves, water, snacks, a flashlight and a charged phone.
- If the pass is closed, wait or take the route the state names. Don't follow a phone map's detour onto side roads or forest roads: they aren't plowed.
Written from the states' own rules (WSDOT, ODOT, Caltrans) in October 2026. Rules change, and the signs on the road always come first.