Frequently Asked Questions

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Chain Laws In Colorado


Winter Tire Tread Requirements for NonCommercial Vehicles


The Colorado Chain Law is the popular term for the requirement for use of tire chains or adequate snow tires on mountain highways during heavy snow conditions. The term is somewhat misleading because chains are not always required. There are two levels of the law that may be invoked as follows.


Chains or adequate snow tires required


This level requires the use of snow tires or traction devices such as cable chains, etc. Snow tires must have the mud and snow (M/S) or all weather rating from the manufacturer on the side wall.


Chains Only


When this level is in effect, use of conventional, steel-link chains is required. Four-wheel drive vehicles are permitted to operate without tire chains.


Studded tires can be used year round in Colorado.


When snow tires are required:


  • Conventional mud and snow tread with (M/S) with or without studs and a minimum tread depth of 1/8".
  • Tires of the all weather type bearing the mark M/S with a minimum tread depth of 1/8".
  • Four-wheel drive vehicles (all four wheels engaged) with adequate tires. Adequate tires for four-wheel drive vehicles include those with conventional tread with a minimum tread depth of 1/8" and those listed in 1) or 2) above.
  • Wavy snow-treads with steel wire protruding.
  • Any conventional tire with a minimum tread depth of 2/32" when used in conjunction with chains as mentioned in "Chain Only" section.


Colorado chain law applies to every state highway, federal highway and interstate throughout the state. When the chain law is in effect, drivers will see signs along the roadway indicating which vehicles should chain-up. In some areas of the state, lighted variable message signs will also alert drivers of the chain-up information.


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.



There are two levels of the chain law that will affect commercial vehicles. A vehicle is considered to be a commercial vehicle if it is used in commerce to transport passengers or property if the motor vehicle:


  • Has a gross combination weight rating of 26,001 lbs. or more inclusive of a towed unit with a gross vehicle weight rating of more than 10,000 lbs.;
  • Has a gross vehicle weight rating of 26,001 or more pounds.
  • Is designed to transport 16 or more passengers, including the driver.


Level 1

This level of chain law implementation requires that all single axle combination commercial vehicles chain-up . All four wheels of the power drive axle must be chained. Cables are not allowed on single drive axle combination commercial vehicles as an alternative traction device. When level 1 of the chain law is in effect, all other commercial vehicles must have snow tires or chains. Level 1 may be implemented at any time there is snow covering any part off the traveled portion of the pavement on an ascending grade.


Level 2

When the chain law is in effect at this level, chains are required for ALL commercial vehicles. This includes trucks exceeding 26,001 lb. weight, and buses or vehicles that are designed to carry 16 or more passengers. Autotransports must comply with the law to the extent possible without causing damage to hydraulic lines. Buses need to chain only two drive wheel tires. (Cables are not allowed on single drive axle combination units, they must use chains!)


Level 2 may be implemented any time there is snow covering the entire traveled portion of the pavement on an ascending grade or when in the discretion of the highway maintenance supervisor (or designee) road, weather or driving conditions make this restriction necessary to protect the safety of the traveling public or minimize occurrence of road closures.


Approved Alternative Traction Devices (ATD's)


Approved ATD's may be used instead of chains. These include wheel sanders (vehicle must carry enough sand to negotiate the hill), or pneumatically driven chains which when engaged, spin under the drive wheels automatically as traction is lost.


The rules and regulations disallow the use of tire cables on commercial vehicles. The following are the only two approved situations in which cables can be used:


  • Tire cables constructed with high strength steel spring cross member rollers that are at least 0.415" diameter or greater can be used instead of chains on commercial vehicles with the exception of single drive axle combination vehicles.
  • On a tandem power drive axle commercial vehicle any type of cable can be used only if there are chains on the outside tires of one of the power drive axles and cables on two or more tires of the other power drive axle.


The Colorado Department of Transportation will be monitoring the use of cables and their effectiveness this winter. The Department can at any time rescind the approval of cables as an ATD.



Colorado has no rule or statute regarding the requirement for chains on trailers. Tire cables are acceptable for use on trailer tires




Trucks placarded for Flammable, Combustible, or Explosives may pass the chain-up signs and install their chains where the pavement is covered by snow or ice, at a safe location outside the traveled portion of the highway.


  • Eastbound I-70: Milepost 180, 182.6, 183.8 (shoulder only), 186.2, 203 (Frisco scenic overlook), 210.8 (three miles below Eisenhower Tunnel).


  • Westbound I-70: Milepost 228 (Georgetown), 221 (Bakerville), 218.5 (Herman Gulch interchange), 195 (Copper Mountain overlook).




Colorado Department of Transportation personnel or law enforcement may control the reentry of vehicles from the chain inspection stations to the state highway to assist and enhance the flow of traffic as assure the safety of the traveling public.



Drivers operating a commercial vehicle as defined in Colorado Department of Transportation’s rule 2 CCR 601-14, SECTION 1.10, with the exception of mobile cranes, being operated on Interstate 70 between milepost 133 to milepost 259 from September 1st to May 31st inclusive, must carry tire chains as defined in §42-4-106(5)(A)(I), C.R.S., alternative traction devices or tire cables may be used in lieu of tire chains.




The chain law shall cease to be in effect where designated by a sign or when bare pavement is encountered on a descending grade.




Drivers of commercial vehicles who ignore the chain law can be fined $500 plus a surcharge for not putting chains on their vehicles when required. A driver can be fined $1000 plus a surcharge if the vehicle is not chained when the law is in effect and as a result blocks the highway. The fines for not carrying chains on your commercial vehicle when required is $50 plus a surcharge.


Remember! Colorado's weather can change dramatically and quickly. Drivers need to be prepared. Call ahead for road conditions and chain-up information for Colorado's major highways at (303) 639-1111

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