Driving I-70 in Winter: A Visitor's Guide

Interstate 70 is the road to almost every ski resort west of Denver, and in winter it's one of the most talked-about drives in the country. It's not dangerous if you prepare, but it rewards people who know the rules and the rhythms. This guide gathers what the Colorado Department of Transportation publishes, in plain words.

The Traction Law

From September 1 to May 31, Colorado's Traction Law season applies on the I-70 mountain corridor between Morrison and Dotsero. When CDOT activates it, usually during or after snow, your vehicle needs one of the following:

• Tires with at least 3/16 inch of tread, rated for mud and snow or winter (marked M+S, M/S, or with the mountain-snowflake symbol)
• Chains or an approved alternative traction device, such as an AutoSock

CDOT strongly recommends four-wheel or all-wheel drive in the mountains, and it can activate the same laws on any state highway when conditions call for it. Check CDOT's Traction Law page for the full list of what qualifies.

The Chain Law

The Passenger Vehicle Chain Law is the last step before a road closes. When it's on, every vehicle needs chains or an approved device, whatever its tires or drive system.

The fines

Driving without proper equipment when the law is active can cost $100 plus a $33 surcharge. If a non-compliant vehicle blocks a travel lane, the fine rises to $500 plus a $157 surcharge.

A note on rental cars: many come with all-season tires. Check the tire markings and tread before you leave the lot, and ask for an AWD or 4WD vehicle with suitable tires.

When to drive, and when not to

Traffic on I-70 follows a predictable weekly pattern, and timing matters more than anything else.

• Westbound to the mountains builds on Friday afternoons, and Saturday mornings can be busy too.
• Eastbound back to Denver builds on Saturday and especially Sunday afternoons, and on holiday Mondays.
• The heaviest weekends are holiday weekends and January and February weekends, but plan for weekend traffic all season.

GoI70, the corridor's traffic program, gives simple advice: go up on Friday, come down after 7 pm on Saturday or Sunday, or stay Sunday night and drive Monday morning. Midweek travel is almost always easier.

Floyd Hill construction

Between Idaho Springs and County Road 65 (mileposts 241 to 248), CDOT is rebuilding I-70 over Floyd Hill. Work began in July 2023. Westbound traffic should move to its new alignment by the end of 2027 and eastbound by the end of 2028, with completion in 2029. Until then, expect lane closures, traffic shifts and 45 mph limits. Occasional blasting holds of about 20 minutes, up to 45, happen on weekdays only: Monday to Thursday from 9 am to 3 pm and Friday from 9 am to noon. When it's finished, the project adds a westbound tolled Express Lane.

The existing I-70 Mountain Express Lanes near Idaho Springs are tolled and open on weekends and holidays.

The tunnel and metering

The Eisenhower–Johnson Memorial Tunnel carries I-70 under the Continental Divide, and at 11,158 feet at its west portal it's the highest point on the entire Interstate Highway System. The two bores opened in 1973 and 1979 and are each about 1.7 miles long. Vehicles carrying hazardous materials must cross Loveland Pass on US 6 instead.

On busy or stormy days, CDOT meters traffic approaching the tunnel with a red-and-green light that changes every four to eight seconds, and meters some eastbound on-ramps at Copper Mountain, Frisco, Silverthorne and Loveland. It feels slow, but CDOT says the actual added delay averages about 3.5 minutes, and it keeps the tunnel moving.

The passes beyond

• Vail Pass (10,662 feet) on I-70 between Copper Mountain and Vail, with grades up to about 7% and frequent winter weather
• Berthoud Pass (11,307 feet) on US 40 to Winter Park, with 6.3% grades, switchbacks and more than 55 mapped avalanche paths
• Rabbit Ears Pass (9,426 feet) on US 40 to Steamboat Springs, with a 6.8% descent on the western side
• Independence Pass on CO 82, the summer road to Aspen, is closed for winter; it closed on October 31, 2026, and Aspen traffic goes around through Glenwood Springs

Our checklist for winter drivers

• Check COtrip.org or call 511 before you leave, and again before the tunnel
• Start with a full tank, water, snacks, a blanket and a charged phone
• Confirm your tires meet the Traction Law, or carry an approved device
• Leave room for trucks on the grades, and use lower gears on long descents
• Never plan a tight connection, like a flight or a dinner reservation, on a Sunday afternoon in ski season

Or leave the driving to us

Plenty of visitors drive I-70 every winter without trouble. But after a long flight, in a car you don't know, with a storm moving in and a family in the back, it's a lot to take on. That's what a private transfer is for: a chauffeur experienced on Colorado's mountain roads, a vehicle equipped for winter, and a departure time planned around the traffic and the forecast.

Every ride is in a luxury full-size SUV (Expedition MAX, Yukon XL, Suburban or similar) or an 11-passenger Ford Transit, with flight tracking, meet and greet at DEN and stops on request. See our routes to Breckenridge, Keystone, Copper Mountain and Winter Park, or book your ride. Heading to Vail or Aspen? Our sister sites Vail Moments and Aspen Moments drive those routes.