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Passenger Vehicle Traction & Chain Laws

If weather conditions require, CDOT can implement Passenger Vehicle Traction and Chain laws. Motorists will be alerted to an active Traction Law or Chain Law by highway signage, or traffic/roadway condition alerts.

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Traction Law (Code 15)

During an active Traction Law (also known as a Code 15), motorists must have either snow tires, tires with the mud/snow (M+S) designation, or a four-wheel/all-wheel drive vehicle. All tires must have a minimum one-eighth inch tread. You can also install chains or an alternative traction device (like AutoSock) to be in compliance with the law if your tires aren't adequate.

    Passenger Vehicle Chain Law (Code 16)

    During severe winter storms, CDOT will implement a Passenger Vehicle Chain Law (also known as a Code 16). This is the final safety measure before the highway is closed.

    When the Passenger Vehicle Chain Law is in effect, every vehicle on the roadway must have chains or an alternative traction device (like AutoSock).


    • Motorists driving with inadequate equipment when a Passenger Vehicle Traction Law or Chain Law is in effect could be fined more than $130.
    • If a motorist blocks the roadway because he/she has inadequate equipment when a Passenger Vehicle Traction Law or Chain Law is in effect, he/she could be fined more than $650.

    Frequently Asked Questions

    Starting Aug. 2, 2019, the legislation updates requirements for drivers using state highways during winter months.

    Specifically, it changed the required minimum tire tread for vehicles on snowy roads to 3/16 of an inch. The statute also says that the minimum tire tread for dry roads is 2/16 of an inch.

    The law reaffirms the department's ability to close state highways during inclement weather, and requires any motor vehicle to have one or more of the following:

    • tire chains;
    • an alternative traction device;
    • four-wheel drive with adequate tire tread;
    • all-wheel drive with adequate tread; and/or
    • tires with manufacturer marking for snow/mud and adequate tread.

    The major change is that these requirements for adequate tire tread and traction control devices now apply to passenger vehicles, whereas they did not before.

    This means every vehicle traveling on state highways must have adequate tire tread and traction-control devices in their vehicle during inclement weather and snow events.

    While the bill specifies the I-70 mountain corridor between Genesee and Dotsero, this does not limit the applicability of the law to this corridor. CDOT traction and chain law apply to all state highways. The legislation speaks to the I-70 corridor because it is a critical highway to keep open, and because the high number of spinouts and crashes that occur along this road between September and May.

    The Colorado State Patrol (CSP) will not proactively enforce the tire tread-depth requirement on vehicles for the following reasons:

    • There is language in the bill that states the tire tread and traction-control device requirements are in place when there are icy and snow-packed conditions.
    • During clear, dry conditions, the existing 2/16-of-an-inch tread applies.
    • The CSP has neither the manpower nor the resources to enforce tire tread requirements on all vehicles traveling state highways during snow events.

    There is language in the bill that directs CDOT and the CSP to meet with stakeholders to discuss options and ideas on how to begin enforcing this law along I-70. Obviously, there are many implications associated with increased enforcement, including:

    • slowing down traffic further on the east side of Vail Pass and at Genesee;
    • resources for enforcement actions;
    • whether there will be additional chain-up stations available for vehicles without traction control devices; and
    • when, where and how possible chain stations will be staffed and funded.

    It may be possible to increase enforcement before next winter, but many policy and fiscal questions remain unanswered at this time as to be able to adequately say when and where additional enforcement would occur.

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