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Chain Controls

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Important notes:

Most vehicles come with ‘all season tires’ which DO qualify as ‘snow tires’ under the Caltrans/CHP regulations. Verfy that your tire says ‘M+S’ on the side. 4 wheel drive or all wheel drive vehicles will NOT need to install chains in the majority of chain control restrictions (see below), but you are still required to carry a set of chains.

Buy chains AND learn how to install them AT HOME before you need them. It’s not fun to learn how to install them in a snowstorm on the side of the road. Pack gloves and hand warmers in your chain box!

Chain Control Definitions

Requirement 1 (R-1): Chains are required on all vehicles except passenger vehicles and light-duty trucks under 6,000 pounds gross weight and equipped with snow tires on at least two drive wheels. Chains must be carried by vehicles using snow tires. All vehicles towing trailers must have chains on one drive axle. Trailers with brakes must have chains on at least one axle.

Requirement 2 (R-2): Chains or traction devices are required on all vehicles except four-wheel/all-wheel drive vehicles with snow-tread tires on all four wheels. NOTE: (Four-wheel/all-wheel drive vehicles must carry traction devices in chain control areas.)

Requirement 3 (R-3): Chains or traction devices are required on all vehicles, no exceptions.

R-1 and R-2 are the most common conditions. A highway will often be closed before an R-3 condition is imposed. Some local areas may use variations of these designations. You must follow the directions on the signs posted for chain controls or any instructions given by Caltrans or CHP personnel at chain control check points, even if these are at variance with broadcast road condition reports or information contained herein.

1 Snow-tread Tires: The California Vehicle Code, Section 558 defines a snow-tread tire as follows, “A ‘Snow-tread tire’ is a tire which has a relatively deep and aggressive tread pattern compared with conventional passenger tread pattern”. Snow-tread tires can be identified by examining the sidewall of the tire where the letters MS, M/S, M+S or the words MUD AND SNOW have been stamped into the sidewall.

2 Tire Traction Devices: The California Vehicle Code, Section 605 defines tire traction devices as follows: “Tire Traction Devices are devices or mechanisms having a composition and design capable of improving vehicle traction, braking and cornering ability upon snow or ice-covered surfaces. Tire traction devices shall be constructed and assembled to provide sufficient structural integrity and to prevent accidental detachment from vehicles. Tire traction devices shall, at the time of manufacture or final assembly, bear a permanent impression indicating the name, initials or trademark of the assembling company or primary manufacturer, and the country in which the devices were manufactured or assembled in final form.”

Please note: The California Department Of Transportation (Caltrans) reserves the right to prevent any vehicle from entering a chain control area when it is determined the vehicle will experience difficulty in safely traveling the area.

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When you load this web page, the chain data is pulled direclty from Caltrans. It should show the same information as any Caltrans-run site such as the Quickmap.