Do I need chains on I-70 in Colorado?

Passenger vehicles usually need snow tires or 4WD/AWD under the Traction Law; chains become mandatory for everyone only when CDOT issues a Passenger Vehicle Chain Law (Code 16), which is rare but happens in the worst storms. Commercial vehicles have their own chain law from Sept 1.

What is the alternative to I-70 over the tunnel?

US-6 over Loveland Pass (11,990 ft) is the hazmat route and is usually worse. When I-70 is closed at the tunnel there is no practical detour; wait in Georgetown, Idaho Springs, or Silverthorne.

I-70 · CO

I-70 through the Colorado mountains: road conditions right now

Denver, CO to Grand Junction, CO

I-70 west of Denver climbs to the Eisenhower–Johnson Tunnels at 11,158 feet, drops to Silverthorne, and climbs again over Vail Pass at 10,662 feet before descending Glenwood Canyon. Colorado's traction and chain laws apply on this stretch every winter.

Checking the forecast, NWS alerts, and DOT feeds for I-70 right now…

Why this stretch is hard in winter

Eisenhower Tunnel approaches and Vail Pass are the two stretches most often closed for crashes, spinouts, or avalanche control.
Colorado's Traction Law (Code 15) requires snow tires, M+S tires with 3/16" tread, chains, or 4WD/AWD from Sept 1 to May 31 between Morrison and Dotsero.
Glenwood Canyon closes for rockfall and, after the 2020 Grizzly Creek fire, for mudslides during heavy rain.
Sunday afternoon ski traffic plus a storm can turn a 2-hour drive into 6.

What this page checks

Hourly forecast at every checkpoint for the time you would be there: temperature, precipitation type and rate, gusts, visibility.
Active National Weather Service watches, warnings, and advisories on the route.
Snow on the ground (NOAA SNODAS) and the Weather Prediction Center winter impact outlook.
Pavement temperature and surface state from state DOT road sensors, when you are leaving within a few hours.
Chain controls, closures, and winter road condition reports from state DOT feeds where they are published openly.
Seasonal closures of mountain roads the router might otherwise use.

Official sources for this corridor

Questions drivers ask about I-70

Do I need chains on I-70 in Colorado?: Passenger vehicles usually need snow tires or 4WD/AWD under the Traction Law; chains become mandatory for everyone only when CDOT issues a Passenger Vehicle Chain Law (Code 16), which is rare but happens in the worst storms. Commercial vehicles have their own chain law from Sept 1.
What is the alternative to I-70 over the tunnel?: US-6 over Loveland Pass (11,990 ft) is the hazmat route and is usually worse. When I-70 is closed at the tunnel there is no practical detour; wait in Georgetown, Idaho Springs, or Silverthorne.

Conditions change by the hour. This page is a planning aid built on public forecasts and DOT feeds; the road authority linked above has the final word on closures and chain requirements.

Other corridors: I-80 across Wyoming · I-80 over Donner Pass · I-90 over Snoqualmie Pass · I-84 through the Blue Mountains · I-15 over Cajon Pass · I-90 across South Dakota · all corridors