Chain-Up Tips for Commercial Vehicles

Chain Law Restrictions

I-70 Chain Law

All commercial vehicles traveling on I-70 between mile points (MP) 133 (Dotsero exit) and 259 (Morrison exit) from Sept. 1 through May 31 must carry sufficient chains to be in compliance with the Colorado chain law.

The Facts


Chains help commercial vehicles traverse the steep climbs often present in the high county. Without chains, vehicles often become disabled, causing traffic delays and sometimes road closures. For the safety of the traveling public, it's critical to use chains to comply with Colorado's chain law.

Passenger & Smaller Commercial Vehicles

A chain law restriction for vehicles weighing less than 16,001 pounds—including passenger vehicles, crossovers, SUVs and small trucks—can be put into effect in Colorado at any time when weather conditions are severe, primarily on roadways with significant ascending and descending grades.

Find Updates

From Sept. 1 through May 31, use the following chain law resources:

Under the Colorado chain law, a commercial vehicle is defined as being used in commerce to transport passengers or property and fitting into one of the following categories:

  • Has a gross combination weight rating of 16,001 or more lbs. inclusive of a
    towed unit which has a gross vehicle weight rating of more than 10,000 pounds; or 
  • has a gross vehicle weight rating of 16,001 or more pounds; or
  • is designed to transport 16 or more passengers, including the driver.

Commercial vehicles operating on I-70 in either direction between mile points 133 (Dotsero) and 259 (Morrison) from Sept. 1 to May 31 must carry sufficient chains at all times to be in compliance with the Colorado chain law.

Chaining Up
Metal chains must consist of two circular metal loops, one on each side of the tire, connected by not less than nine evenly-spaced chain loops across the tread.  Commercial vehicles that have four or more drive wheels must chain four wheels.  Dual tire chains are acceptable.

Alternate Traction Devices (ATDs)
Approved ATDs in Colorado are wheel sanders, which carry enough sand to get the vehicle through the restricted area; pneumatically driven chains, which spin under the drive wheels automatically as traction is lost; and textile traction device (TTD), a fabric boot which encompasses the tire.  Currently, the only TTD that has been approved for use on Colorado state highways is the AutoSock TM.

Tire Cables
With only two exceptions, Colorado chain law rules do not permit tire cables as alternate traction devices.  The exceptions are: 1) tire cables with high strength steel cross member rollers 0.415" or greater in diameter, which can be used on all commercial vehicles except single drive axle combinations; and 2) on a tandem power drive axle commercial vehicle, where any type of cable can be used only if there are chains on the two outside tires of one of the power drive axles and cables on two or more tires of the other power drive axle.

Station Locations
I-70 Eastbound: mile points 178, 183, 184 (shoulder), 187 (shoulder), 195, 203 (scenic area), 205, 219, 228, 241, 251, 289, 343
I-70 Westbound: mile points 358, 263, 260, 254 (Buffalo Overlook), 228, 223, 221, 219, 213, 197, 179 
I-25 Northbound: mile point 157
I-25 Southbound: mile point 172

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. Auto transports 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 and 259 from September 1 to 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 not chaining up and subsequently blocking the highway is $1,000 plus a $157 surcharge.