Chain Up Tips

This information applies to Colorado state, federal and interstate highways.

Colorado Chain Up Tips Flyer

Carrying Chains on I-70

Commercial vehicles driving on I-70 between mileposts 133 (Dotsero) and 259 (C-470) from Sept. 1–May 31 must carry sufficient chains at all times to be in compliance with the Colorado chain law. This is the only area in Colorado in which chains must be carried during the specified season.

CMV by Definition

Commercial Motor Vehicle (CMV) for purposes of these rules means a vehicle having a manufacturer's gross vehicle weight restriction (GVWR) or GCWR of at least 16,001 pounds and used in commerce on public highways, or a GVWR or GCWR of at least 16,001 pounds and used to transport at least 16 passengers, including the driver

Chain Law

To travel on a state highway when the Commercial Motor Vehicle Chain Law is in effect, a CMV must have chains or alternate traction devices (ATDs) on at least four of the drive wheel tires, or all of the drive wheel tires if the vehicle has fewer than four drive wheel tires. Buses are required to chain or have ATDs on two drive wheel tires.

Chain Law Notifications

The applicable traction and chain law requirements will be messaged out through the CDOT notification process, including Variable Message Signs, static signs, other official traffic control devices as appropriate, the CDOT travel website, telephonic messaging system, email, text notifications, and other technologies. Notifications will specify by mile points and by exit number when chains are required.

Chaining Up

The Commercial Motor Vehicle Chain Law is a requirement for all large vehicles to affix chains or alternate traction devices (ATDs) to all drive tires (up to four).

Tire Chains

Tire chains include but are not limited to metal chains which consist of two circular hoops, one on each side of the tire, connected by not less than nine evenly spaced chains across the tire tread. Tire chains shall meet the SAE classification as by the National Association of Chain Manufacturers. Clip-on chains are not permitted, nor is any other device not designated as an approved ATD.

Tire Cables

Tire cables are traction devices made of steel cable as opposed to steel chain link, which has high strength steel cross member rollers 0.415" or greater in diameter, which may only be used on passenger vehicles. Tire cables on CMVs are not permitted.

Alternative Traction Devices

Alternative Traction Devices (ATD) must be one of the ATD included in the CDOT Approved Product List (APL). Drive wheel sanders and pneumatically driven chains are also allowed.

Passing Requirements When Chain Law is Active

CMVs shall be restricted to the right lane unless encountering a stalled or slower moving vehicle that would result in the loss of traction, in which case the CMV may utilize the left or center lane to pass if the movement can be made safely and without interference with other traffic. Any such pass must be completed without losing traction and the CMV must return immediately to the right lane upon completion of the pass.