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Traction Devices - Chaining Tire

What are tire traction devices?

Tire traction devices are defined in the California Vehicle Code (VC) Section 605 as “devices or mechanisms having a composition and design capable of improving vehicle traction, braking, and cornering ability upon snow or ice-covered surfaces,” and include conventional link-type tire chains and cable chains, as well as other less conventional devices such as “Spikes Spyder.” When the term “chains” is used here, it means any “tire traction device” unless it specifically states link-type chain.

What are Automatic Traction Devices (A.T.D.'s) and are they legal in California?

Automatic Traction Devices (A.T.D.’s) are used primarily on commercial vehicles, emergency vehicles, and busses. ATD’s are devices mounted under the vehicle that sling chain segments under the inside drive wheels. These devices can be deployed by the driver when the need for extra traction is required. While they are legal in California and have been approved as a direct one-on-one replacement for conventional chains, vehicles with only ATD’s may be required to add additional chains to outside wheels to comply with the California Chain Requirements Chart

Are chains required on the inside “duals” on 2-axle vehicles (trucks, buses, RVs, etc.)?

Not usually, but under severe conditions, the California Department of Transportation (Caltrans) may require chains on the inside duals if conditions warrant. (If conditions are this severe, it may be better to postpone the trip.)

Where are chains required?

Chains are most often required in the higher mountain passes of northern California, such as Interstate 5 north of Redding, Interstate 80 over Donner Pass between Sacramento and Reno, Nevada, and US Highway 50 over Echo summit between Lake Tahoe and Sacramento. Chains are also sometimes required on State Route 58 near Tehachapi between Bakersfield and Mojave, Interstate 15 over Cajon Pass between Victorville and San Bernardino, and Interstate 5 over Tejon Pass between Los Angeles and Bakersfield. However, snow can fall unseasonably at higher elevations at many locations within California. Chains may be required at any time at these higher elevations when conditions warrant.

Motorists are advised to check the Caltrans web site at for current road conditions. Motorists may also call the statewide Caltrans road information number at 800-427-7623 (outside California: 916-445-7623) or the Bay Area-Reno/Tahoe corridor road information number at 916-817-1717.

Are “all-weather” or “all-terrain” tires the same as “snow” tires?

They may be. Snow tires have the designation “Mud & Snow” or an abbreviation such as “M-S,” “M+S,” or “M/S” marked on the tire sidewall. Tires without this designation are not considered snow tires. Snow tires must also have at least 6/32-inch (3/16”) of tread depth (about 1/2 of the original tread depth).

Are cable chains permitted?

Usually. They are permitted for passenger cars and light trucks under virtually all conditions. Cables are not as effective as link-type chain under severe conditions at higher elevations and steep grades for “big-rigs” and may not be permitted depending on local conditions as determined by Caltrans. Whenever chain controls are posted over Donner Pass on Interstate 80, heavy trucks are usually required to have link-type chain on at least the main drive axle.