Snow tires provide improved control of a motor vehicle under snowy conditions. California recognizes snow tires for use on passenger vehicles and light trucks under R-1 (chains required except for vehicles with snow tires unless pulling a trailer) or R-2 (chains required except for 4-wheel drive with snow tires) conditions, according to the California Highway Patrol. Check with the California Department of Transportation's website for up-to-date highway conditions (see Resources).
Snow tires provide added traction in snow or slush with the presence of regularly spaced metal studs or specially designed treads and grooves. The design aids in directing snow and slush away from the tire. A special formulation of rubber, designed to maintain the appropriate pliability in cold weather, adds to the usability of the tires.
Purchase snow tires in the appropriate size for the vehicle, using the manufacturer-suggested tire specifications. Check the tread depth regularly. Under California law, snow tires must carry a minimum of 6/32-inch tread depth.
Snow tires must carry the identifying label "Snow Tire," the designation "Mud and Snow" or some variation of the letters M and S on the sidewall to be acceptable as snow tires in California. They come in studded, studless and "pinned for studs" configurations.
Studless tires take advantage of newer technology to provide the benefits of a studded tire through materials and design without pavement-damaging studs. A tire that is pinned for studs offers preset positions in the tread for insertion of metal studs with a special tool when conditions warrant. Whether permanent or temporary, studs may not exceed more than three percent of the tire surface contacting the road.
On bare pavement, studded snow tires can damage the road surface. California, like many states, regulates studded snow tire use. Between November 30 and April 1 of each year, California law permits drivers to use snow tires with studs anywhere in the state. Drivers may not drive outside of designated snow areas with studded tires beyond that range of dates, unless the studs are retracted.
Install snow tires on all four wheels. Maximum stability, traction and control result from matching tires on both driving and braking axles.
At certain elevations or under particularly adverse conditions, California highway authorities may deem snow tires insufficient for safe driving. R-3 conditions require snow chains for all vehicles. Even four-wheel drive vehicles should carry snow chains when traveling in areas likely to experience periods of R-3 conditions.
