California has approved the AutoSock as an alternative traction device to chains except if/when DOT determines that chains are required and no other traction device will suffice.
Here is the approval from the Highway Patrol and DOT: CHPTraction and ChainRequirements
Caltrans official wording from their site approves traction devices but more information is available PDF above.
California DOT: http://www.dot.ca.gov/hq/roadinfo/chcontrl.htm
TYPES OF CHAIN CONTROLS:
During the winter months, motorists may encounter traction chain controls in the mountain areas within California. When chain controls are established, signs will be posted along the road indicating the type of requirement. There are three requirements in California.
Requirement One (R1): Chains, traction devices or snow tires are required on the drive axle of all vehicles except four wheel/ all wheel drive vehicles.
Requirement Two (R2): 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 Three (R3): Chains or traction devices are required on all vehicles, no exceptions.
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.
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.”
If you would like to view a full version of the California Vehicle Code it can be located at the following location, under California Law:http//www.leginfo.ca.gov
The Department of Transportation does not sell nor recommend specific brands of tire chains. It is best to check your vehicle manufacturer’s specifications for use of tire chains/traction devices.
A chart depicting the proper placement of traction devices is available in Adobe Portable Document format. You can easily print this file for your records. When printing the file use the printer button in the Acrobat Reader not the printer button from your browser. If you do not have the most current version of Acrobat Reader from Adobe click here to download.