Chain controls go up on California mountain highways when snow and ice hit the road. Caltrans uses three levels, R-1, R-2 and R-3, and the level decides whether your car has to chain up. Here is what each one means and what to do.
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R-1, R-2 and R-3 at a glance
| Level | What it means | Who can skip chains |
|---|---|---|
| R-1 | Chains or snow tires required | Cars and light trucks under 6,000 lbs with snow tires on at least the two drive wheels |
| R-2 | Chains required on most vehicles | 4WD/AWD under 6,500 lbs with snow tires on all four wheels. You must still carry chains. |
| R-3 | Chains required on all vehicles | Nobody. The road is often closed before R-3. |
What counts as a snow tire
- The sidewall must say M+S, M/S, M-S or “Mud & Snow”.
- At least 6/32 inch of tread, about half of a new tire.
- No marking means it is not a snow tire under the rules, even if it is a good all-season.
4WD and AWD: the catch
AWD only gets you through R-2 if all four tires are snow tires, and you must carry chains to enter a chain control area at all. If conditions get worse or you lose control, you have to stop and put them on. AWD helps you climb; it does not help you stop.
If you need to chain up
- Pull fully off the road at a signed chain-up area, not in a travel lane.
- Chains go on the drive wheels. Check your owner’s manual; some cars do not allow chains at all and need cables or socks.
- Keep it slow: the posted speed with chains is usually 25 to 35 mph.
- Licensed chain installers work many chain-up areas. They are independent, not Caltrans employees, and they cannot sell or rent chains. Get a receipt with their badge number.
- No chains? You will be turned around to a lower elevation.
Before you leave
- Check the Road and Chains lights for your mountain on Ski Lots.
- Buy chains before the mountains. Shops near the snow sell out and charge more on storm days.
- Practice putting them on once in your driveway.
Sources: Caltrans chain requirements; Lake Tahoe Visitors Authority, Weathering the Storm. Rules can change; always follow posted signs and CHP.