Despite warm weather in Colorado’s lower elevations, Monday marked the start of the state’s Chain Law season, according to a statement released by the Colorado State Patrol on Monday.

From now through May 31, all drivers must comply with the Colorado Chain Law and Passenger Vehicle Traction Law statewide.

The law requires all commercial vehicles over 16,000 pounds or carrying 16 or more passengers (driver included) to carry chains or approved traction devices on the following major routes:

• Interstate 70 from Morrison to the Utah border
• Colorado Highway 9 from Frisco to Fairplay
• U.S. Highway 40 from Empire to the Utah border
• U.S. Highway 50 from Salida to the Utah border
• U.S. Highway 160 from Walsenburg to the New Mexico border
• U.S. Highway 285 from Morrison to the New Mexico border
• All of U.S Highway 550

Fines for noncompliant commercial vehicles are up to $500 plus a $79 surcharge, or up to $1,000 for blocking traffic.

Passenger cars and trucks (under 16,001 pounds) traveling I-70 between Morrison and Dotsero must have chains for at least two tires, an alternative traction device, or tires with 3/16-inch tread labeled “All Weather” or “Mud and Snow” by the manufacturer. Failing to comply risks a $50 fine and a $17 surcharge.

The Colorado State Patrol will hold a commercial vehicle chain check on I-70 near Dotsero on Thursday to ensure vehicles are equipped. Drivers are advised to check updates regularly and ensure proper equipment is onboard before traveling Colorado’s mountain roads.

To learn more, visit csp.colorado.gov/chain-law-information.