Stay safe and avoid hundreds of dollars in fines by obeying these well-intended laws.

The leaves are turning, and the temperatures are dropping. These are sure signs of fall, and winter is right on its heels. But as you pack your snow gear, make sure you're prepared and you've got the gear for your tires to be safe on the roads.

Colorado Department of Transportation (CDOT) issues the chain laws (or traction laws). Whether to help motorists prepare for winter, CDOT encourages all drivers to put your car to the test with the Traction Law Tree. It might be helpful to keep this fact sheet handy in your glove box.

"Colorado's Chain Law is not just for Large Commercial Vehicles. All vehicles need to be prepared to have adequate tires and equipment when traveling in Colorado during the winter," says Colorado State Patrol.

Any vehicle on I-70, traveling east or west, between milepost 133 (Dotsero) and milepost 259 (Morrison) must follow the following laws September through May: 

  • Any vehicle operating with a GCWR/GVWR of 16,001 pounds or more must carry sufficient chains (traction devices) for the type of vehicle being driven to be in compliance with the chain law requirements should they go into effect.
  • Any two-wheel drive vehicle with a GCWR/GVWR less than 16,001 pounds must have tire chains for two or more drive tires, OR an approved ATD for two or more drive tires, OR tires with a tread depth of at least 3/16-inch and which are rated for either “All weather” or “Mud and Snow” by the manufacturer.
  • Any four-wheel drive motor vehicles with a GCWR/GVWR that is less than 16,001 pounds must have tires with a tread depth of at least 3/16-inch and are adequate for winter driving conditions.

CDOT uses electronic roadway signs to notify travelers of any traction or chain laws in effect on Colorado roads. The key laws for noncommercial vehicles are:

  • Traction Law (Code 15) — Drivers will need to 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.
  • Passenger Vehicle Chain Law (Code 16) — This final safety measure before the highway is closed requires every vehicle to have chains or an alternative traction device (like AutoSock).


In 2014, one of the worst traffic delays on the I-70 Mountain Corridor was caused by unprepared motorists. Severe delays were caused by 22 vehicles spinning out and causing crashes — 19 of those vehicles had worn tires.

For more information on tire safety, different kinds of tires, and tire FAQs, visit CDOT's Tire Safety. You can also take steps to prepare your car for winter

Even if you have the required traction, mishaps happen. Do you know what to do if you get your car stuck in the snow

What else do you do to prepare your car for snow season? Share your tips in the comments below.