When the chain law is in effect, drivers will be notified which vehicles must chain up and where by the following means: electronic message signs along the roadway, 511 traveler information, www.cotrip.org, and media outlets. Metal chains must consist of two circular metal loops, one on each side of the tire, connected by not less than nine evenly spaced chains across the tread. Commercial vehicles having four or more drive wheels must chain four wheels.
Dual tire chains are acceptable. Approved alternative traction devices include wheel sanders and the AutoSock. Also tire cables are not permitted by law as an alternative traction device but there are two exceptions that can be found at www.cotrip.org. Chain Law Level 1; All single drive axle combination commercial vehicles must chain all four driver wheels; cables are not permitted as ATD’S. All other commercial vehicles must have snow tires or chains.
Level 1 may be implemented any time there is a snow covering any part of the travelled portion of pavement on an ascending grade. Chain Law Level 2; All commercial vehicles must chain up. Single drive axle and tandem drive axle combination commercial vehicles must chain four drive wheels.
Auto transports must comply to the extent possible without causing damage to the hydraulic lines. Busses must chain two drive wheels to comply. Level 2 may be implemented any time there is snow covering the entire travelled portion of pavement on an ascending grade, or when driving conditions dictate that this level is necessary.
Commercial vehicles traveling on I-70 in either direction between milepost 133 (Dotsero) and 259 (Morrison) from Sept. 1 from May 31 must carry sufficient chains at all times to be in compliance with the Colorado chain law. For more information, go to CDOT’s Web site at