COLORADO

Larger Vehicles, Including Recreational and Commercial Motor Vehicles

As of August 7, 2024, all commercial motor vehicle drivers must carry chains from September 1 to May 31. This applies to vehicles with a combined weight of more than 16,000 lbs used in commerce or as transport for at least 16 passengers (including the driver) on public highways. View the Colorado chain up tips(opens in new window)(consejos para colocar cadenas en Colorado)(opens in new window) handout for more information on what must be carried by CMVs.

Commercial vehicles and buses have a larger footprint on roadways where chains are required. CMVs must carry chains or ATDs on all the following roads regardless of current weather:

• I-70 west of milepost 259 (Morrison) to the Utah border.
• Colorado Highway 9 mile post 63 to milepost 97 (Frisco to Fairplay).
• Route 40 milepost 256 (Empire) to the Utah border.
• U.S. Route 50 milepost 225 (Salida) to the Utah border.
• U.S. Route 160 milepost 304 (Walsenburg) to the New Mexico border.
• U.S. Route 285 milepost 250 (Morrison) to the New Mexico border.
• All of U.S Route 550.

Those required to chain 4 drive tires:

• Straight Trucks: 4 tire chains, 4 AutoSocks, 4 tire cables 0.415 diameters or greater, auto chains, or sanders.
• Single Drive Axle Combinations: 4 tire chains, 4 AutoSocks, auto chains, or sanders. No cables are allowed.
• Tandem Drive Axle Combinations: 4 tire chains, 4 AutoSocks, 4 tire cables 0.415 diameter or greater, auto chains, or sanders. If chains are on the 2 outside tires of one drive axle, any tire cable may be used to cover 2 tires on the other drive axle. AutoSocks may be used to cover 2 tires on the other drive axle. AutoSocks and tire cables cannot be used together.
• Auto Transporters: 4 tire chains, 4 AutoSocks, 4 tire cables 0.415 or greater, auto chains, or sanders. Do not use chains if use places hydraulic lines at risk of damage (alternative traction devices (ATDs) may be used to mitigate the risk). Travel will be restricted if the vehicle is unable to chain.

Those Required to chain 2 drive tires:

• Buses: 2 tire chains, 2 tire cables 0.415 diameters or greater, 2 AutoSocks, auto chains, or sanders.
• Hot shot trucking: Traditional motor vehicles (such as pickup trucks) that are pulling trailers and meet the above-listed weight criteria must also carry chains. 2 tire chains for singles (to affix to rear tires). Exception: Duallies need 4 tire chains.

Idaho

The law only applies to commercial vehicles over 26,000 pounds on mountain passes, most notably on I-90 east of Coeur d’Alene and on US-12 at the Montana border.

MONTANA

When the Department of Transportation determines tire chains or traction equipment are required, all vehicles towing a trailer (towing units) must apply chains to the driver wheels of one axle.AutoSock’s are an approved alternative to tire chains. Designated chain-up and removal area signs are posted in areas where tire chains may be required. Ref: MCA 61-9-406

Studded winter tires are permitted in Montana from October 1 to May 31 of the following year, except that one of those tires may be used for a spare in case of tire failure. School buses equipped with such tires are permitted from August 15 to June 15 of the following year. Ref: MCA 61-9-406

Between October 1 and April 30 of the following year, towing units 26,001 GVW or greater must carry tire chains or an approved traction device when traveling in an area where tire chains may be required. Note: This does not apply to a vehicle with four-wheel drive. Ref: MCA 61-9-436

A complete guide for which highways chains are required:  Chain Guide

WASHINGTON

Chain Requirements for Vehicles Over 10,000 Pounds

Tire Chain Requirements for Vehicles Over 10,000 Pounds (GVW).