Winter in California often brings hazardous driving conditions in mountainous regions, making traction devices crucial for safety. Here’s everything you need to know about chain requirements in California for 2025, based on the latest updates from Caltrans.

Chain Control Levels Explained

Caltrans employs three levels of chain control, indicated by road signs in affected areas:

• Requirement 1 (R-1):
  Chains are mandatory on all vehicles except passenger vehicles and light-duty trucks under 6,000 pounds gross weight with snow tires on two drive wheels. Vehicles towing trailers must use chains on one drive axle, and trailers with brakes need chains on one axle.
• Requirement 2 (R-2):
  Chains or alternative traction devices are required for all vehicles except four-wheel or all-wheel drive vehicles equipped with snow-tread tires on all four wheels. These vehicles must still carry chains in chain control areas.
• Requirement 3 (R-3):
  Chains or traction devices are required on all vehicles, with no exceptions. Highways are usually closed before reaching this level.

Chain Installation Guidelines

• Stop and Install Chains:
  When you see a “Chains Required” sign, pull off the road safely to install chains. You have about a mile before checkpoints. Stopping in traffic lanes is prohibited.
• Use of Chain Installers:
  Independent chain installers, not employed by Caltrans, can assist you. Always request a receipt and note the installer’s badge number for future reference. Installers cannot sell or rent chains.
• Removing Chains:
  Wait until you pass a “End of Chain Control” sign and use a safe pull-off area to remove them.
• Traction Devices Allowed:
  In addition to traditional link-type chains, alternatives such as cable chains, textile snow chains, wheel hub-attached chains, and automatic tire chains are permitted if they meet California Vehicle Code Section 605.

Winter Safety Tips

• Drive Slowly:
  The speed limit in chain control areas is reduced to 25–30 mph to ensure safety.
• Check Road Conditions:
  Use the Caltrans Highway Information Network (CHIN) at 800-427-7623 or visit Caltrans Quickmap for real-time updates on traffic, closures, and chain controls. You can also get California weather forecasts here.
• Snow-Tread Tires:
  Look for the "M+S" or "Mud and Snow" marking on your tires to confirm they meet California’s snow-tread requirements.

Truck and Trailer Specifics

• Chaining Requirements:
  Trucks and trailers must follow specific guidelines, including chaining drive axles and trailer axles with brakes. Super single tires require chains on all drive wheels.
• Semi-Trailers:
  Chains are required on one axle of a semi-trailer, regardless of the number of axles.

Be Prepared for 2025

California winters demand preparation, and understanding chain requirements ensures safe travel. Always carry chains when entering chain control areas, even if your vehicle is exempt under certain conditions. Stay informed and prioritize safety on the roads this winter.

For more information, visit the Caltrans website or consult the full California Vehicle Code.