Truckers trekking through some parts of Colorado will need to make sure that they have chains on board in just a couple of weeks.

The Colorado Department of Transportation (CDOT) requires that commercial vehicle drivers traveling on I-70 between mile markers 133 (Dotsero) and 259 (Morrison) carry sufficient chains from September 1 through May 31 each year.

Chains are not required for trailers, only for trucks, according to Colorado law.

When the chain law is in effect, drivers will be notified via electronic message signs, 511 traveler information, www.cotrip.org, and media outlets.

“Chains must consist of two circular metal loops, one on each side of the tire, connected by not less than 9 evenly-spaced chain loops across the tread. Commercial vehicles that have 4 or more drive wheels must chain 4 wheels. Dual tire chains are acceptable,” the Colorado Department of Transportation states. 

CDOT has two levels of chain law that can be implemented due to weather conditions:

CHAIN LAW LEVEL 1/CODE 17: All single drive axle combination commercial vehicles must chain all four drive wheels; cables are not permitted as ATDs. All other commercial vehicles must have snow tires or chains. Level 1/Code 17 may be implemented any time there is snow covering any part of the traveled portion of pavement on an ascending grade.

CHAIN LAW LEVEL 2/CODE 18: All commercial vehicles must chain up. Single drive axle combination and tandem drive axle commercial vehicles must chain four drive wheels. Autotransports must comply to the extent possible without causing damage to hydraulic lines. Buses must chain two drive wheels to comply. Level 2/Code 18 may be implemented any time there is snow covering the entire traveled portion of pavement on an ascending grade, or when driving conditions dictate that this level is necessary to protect safety and to minimize road closures.

The fine for not carrying chains on I-70 between mileposts 133–259 from September 1–May 31 is $50 plus a $17 surcharge. Statewide, the fine for not chaining up when the chain law is in effect is $500 plus a $79 surcharge. The fine for blocking a highway as a result of not chaining up is $1,000 plus a $157 surcharge, according to CDOT.

Chain-Up Station Locations:

• I-70 Eastbound: Mile markers 178, 183, 184 (shoulder), 187 (shoulder), 195, 203 (scenic area), 205, 219, 228, 241, 251, 289, 343
• I-70 Westbound: Mile markers 358, 263, 260, 254 (Buffalo Overlook), 228, 223, 221, 219, 213, 197, 179
• I-25 Northbound: Mile marker 159 
• I-25 Southbound: Mile marker 172

You can check www.cotrip.org for information on when the chain law begins and ends.