Winter Ready Checklist

Print this and keep it in the glovebox. Last verified November 1, 2026. Rules can change, so check the agency links in our stud and chain rules guide before you rely on them.

Tires

Tread depth: penny test. Lincoln's head upside down; if you can see all of his head, the tread is below 2/32" and the tire needs replacing.
For snow, more tread matters. Around 6/32" is a commonly cited minimum for good snow traction.
Check pressure cold (parked three hours or more). Pressure drops roughly 1–2 psi for every 10°F.
Inflate to the number on your door placard, not the number on the sidewall.
Know what you're running: M+S, All Season, or the three-peak mountain snowflake (3PMSF) symbol.
Remember: the snowflake symbol is a snow traction rating. It doesn't certify ice braking.

Studs: know your dates

Idaho: Oct 1 – Apr 30
Washington: Nov 1 – Mar 31 ($137 fine out of season, no individual exceptions)
Oregon: Nov 1 – Mar 31 ($165 fine out of season)
Montana: Oct 1 – May 31
Crossing the ID–WA line? Each state's dates apply while you're in it. Plan around the shorter window.

Chains

Chains in the vehicle, even with AWD/4WD. In Washington, AWD/4WD only gets out of a Chains Required sign if you're carrying chains.
Studs don't count as chains when a Washington sign says chains.
Practice fitting your chains in the driveway, not on the shoulder at Snoqualmie.
If your owner's manual says not to use chains, check WSP's list of approved alternative traction devices.
Towing in Montana? Chain areas such as I-90 westbound at Lookout Pass can require chains on towing units.

Before you leave

Check the pass report: WSDOT, Idaho 511, Montana MDT.
Know the sign levels: Traction Tires Advised → Traction Tires Required → Chains Required → Chains Required on All Vehicles.

Caretier Tires summarizes public agency information. This isn't legal advice. Full sources are in our stud and chain rules guide. www.caretiertires.com