Reading a Chain Control Sign

R-1, R-2 and R-3 are not severity ratings for the weather. They are instructions about your vehicle. Which one is posted decides whether you can keep driving as you are, whether you need to put something on the tires, or whether the answer is simply no.

The three levels, as Caltrans defines them

• R-1: "Chains are required on all vehicles except passenger vehicles and light-duty trucks under 6,000 pounds gross weight and equipped with snow tires on at least two drive wheels."
• R-2: "Chains or traction devices are required on all vehicles except four-wheel/all-wheel drive vehicles with snow-tread tires on all four wheels."
• R-3: "Chains or traction devices are required on all vehicles, no exceptions."

Caltrans notes that R-1 and R-2 are the most common conditions, and that a highway will often be closed before an R-3 condition is imposed. In practice, if you are seeing R-3, the more useful question is whether the road is about to shut rather than whether your tires qualify.

The detail that catches all-wheel-drive owners

Read R-2 again. The exemption is for four-wheel or all-wheel drive with snow-tread tires on all four wheels. All-wheel drive with ordinary all-season tires is not the exempt category, and neither is four-wheel drive on three snow tires and a spare. All-wheel drive helps you accelerate; it does very little for stopping and nothing for cornering on ice. The number of people who find this out on a downhill curve above Kingvale is why the requirement is written the way it is.

What the law says

Vehicle Code section 27459 makes it unlawful to operate a vehicle on a portion of highway signed for the requirement of tire traction devices without them, and gives the Department of Transportation and local authorities the authority to impose that requirement. The sign is the law here. There is no discretion built into it for a confident driver in a capable vehicle — the exemptions are the ones written into the level that is posted, and nothing else.

Carrying versus fitting

Under R-1, a light vehicle with snow tires on the drive wheels is exempt from fitting chains but is expected to carry them. Under R-2, four-wheel and all-wheel drive vehicles in chain control areas are expected to carry traction devices even when exempt from using them. The reason is practical rather than bureaucratic: conditions change while you are on the pass, and the level can be raised behind you.

Stopping to put them on

Pull completely off the roadway to the right; do not stop in a traffic lane. That instruction exists because a stopped vehicle in a lane on a snowy grade is how a chain control area turns into a closure. Fit chains before you need them rather than after you have lost traction, since the place you actually need them is rarely a place you can safely stop. On the far side, drive past the signs reading End of Chain Control and find a pull-off before taking them off — chains on dry pavement damage both the chain and the car.

The people at the roadside

Chain installers working in the control areas are independent businesspeople, not Caltrans employees, and they are not permitted to sell or rent chains. If you use one, get a receipt and note the installer's badge number on it, which is what Caltrans itself advises — it is the thing that resolves a misunderstanding later.

Where insurance fits into a winter pass

Sliding into a guardrail, another vehicle, or a snowbank is a collision loss on your own vehicle and requires collision coverage to be repaired. A chain that breaks and beats up your own fender well is usually a physical-damage question too, and how a given carrier classifies it can vary, so ask yours rather than assuming. If you make this drive several times a winter and you are carrying liability only, that is worth revisiting before December.

Have collision priced before ski season and decide with the actual number in front of you.