California Chain Controls Explained: R1, R2, R3 and Winter Tires
California chain controls have three levels. R-1: chains or traction devices are required on the drive axle, but vehicles with snow tires (at least 6/32 inch of tread) and four- or all-wheel-drive vehicles are exempt. R-2: chains are required on all vehicles except four- or all-wheel-drive vehicles with snow tires on all four wheels. R-3: chains are required on all vehicles with no exceptions. Every vehicle must carry chains in a chain control area.
Chain control levels
| Level | Requirement | Exempt |
|---|---|---|
| R-1 | Chains, traction devices or snow tires on the drive axle | 4WD/AWD vehicles; vehicles with snow tires on the drive axle |
| R-2 | Chains or traction devices on all vehicles | 4WD/AWD with snow tires on all four wheels (must still carry chains) |
| R-3 | Chains on all vehicles | None. Roads are often closed at this point |
Before a mountain trip
- Check tread depth: at least 6/32 inch to count as snow tires (how to measure).
- Buy chains that match your exact tire size, and practice fitting them at home.
- Check your owner's manual: some cars with low-profile tires allow only certain cable chains or textile socks.
- Set tire pressures cold to the door placard value; pressure drops in mountain cold (why).
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Frequently asked questions
Do I need chains if I have AWD in California?
At R-1 and R-2, a four-wheel or all-wheel-drive vehicle with snow tires on all four wheels can usually proceed without chains, but it must still carry chains in the chain control area. At R-3, everyone needs chains.
What counts as a snow tire for chain controls?
A tire marked M+S (mud and snow) or with the three-peak mountain snowflake symbol, with at least 6/32 inch of tread.
How fast can I drive with chains on?
Chain control areas have posted limits, typically 25 or 30 mph.
Where can I check chain controls before I leave?
Caltrans QuickMap and the Caltrans road conditions line at 1-800-427-7623 show current chain controls.
Related guides
- When to Replace Tires: Tread Depth, the Penny Test and California Law — California's legal minimum is 1/32 inch, but wet grip fades long before. The penny and quarter tests, wear bars and other reasons to replace.
- How to Read a Tire Size: What 225/65R17 98H Means — A plain guide to the numbers on your tire sidewall: width, aspect ratio, construction, rim diameter, load index, speed rating, DOT code and the UTQG rating.
- Tire Pressure Light On? What the TPMS Warning Means and What to Do — A steady TPMS light means a tire is low; a flashing one means a system fault. How to check pressure, find the right psi and handle cold mornings.