California reference

California R-1, R-2 and R-3 chain controls

R-1, R-2 and R-3 are escalating Caltrans traction-control levels. The posted roadside requirement and Caltrans route report are authoritative.

What to know

R-1 generally requires chains or approved traction devices except on qualifying snow-tread vehicles.
R-2 generally requires chains or approved devices except on qualifying four-wheel/all-wheel-drive vehicles with snow-tread tires on all four wheels.
R-3 requires chains or traction devices on all vehicles, with no four-wheel-drive exception.
Caltrans may close the road before or during severe conditions; carrying chains does not guarantee passage.

Primary references

California Vehicle Code §27459 authorizes posted chain requirements. Caltrans reports R-1, R-2 and R-3 control levels.

Law or official guidance Current DOT conditions

Fitment safety

Follow the vehicle manual and the traction-device maker's exact fitment table. Install only on the axle positions they permit, stop if anything rubs, and respect the device's maximum speed.

Laws, agency guidance and device approvals can change. Verify before each trip. Roadside signs and law-enforcement direction control.