Vehicles
Do I need chains with AWD, 4WD or snow tires?
Live chain control
Updated · Caltrans / NDOT data via Snowy Roads, refreshed every 3 minutes. Tap a chip for checkpoints, cameras and signs.
Usually not, but you must carry them. Under R-1 and R-2 chain control, a 4WD or AWD vehicle with snow-tread tires (M+S or the three-peak mountain snowflake) on all four wheels is exempt from chains. Under R-3, everyone chains up. Today's live requirements on I-80 and US-50 are shown above.
The rule, level by level
Caltrans' chain control levels each carry their own exemption, and drivetrain alone never gets you out of chains: the tires matter at every level.
- R-1: chains are required on all vehicles except passenger vehicles and light-duty trucks under 6,000 pounds gross weight with snow tires on at least two drive wheels. Chains must be carried by vehicles using snow tires. If your AWD is on plain tires without an M+S marking, expect to chain up even at R-1.
- R-2: chains or traction devices are required on all vehicles except four-wheel-drive and all-wheel-drive vehicles with snow-tread tires on all four wheels. 4WD and AWD vehicles must carry chains.
- R-3: chains or traction devices are required on all vehicles, no exceptions. Your Outback on studless winter tires puts chains on like everyone else.
A two-wheel-drive car with snow-tread tires is exempt at R-1 only. Read R-1 vs R-2 vs R-3 explained for the full table.
What counts as a snow-tread tire
The California Vehicle Code definition Caltrans uses: a tire with a relatively deep and aggressive tread pattern, identified by the letters MS, M/S, M+S or the words MUD AND SNOW on the sidewall. The three-peak mountain snowflake symbol marks a tire that meets a tougher snow-traction test and always qualifies.
- Most all-season tires are marked M+S, so a stock Subaru, RAV4, CR-V or Model Y on its factory all-seasons usually qualifies. Look at the sidewall to be sure.
- Summer or performance tires carry no marking and do not qualify, no matter how new they are.
- All four tires must qualify for the R-2 exemption. A pair of winter tires on the front axle does not count.
- Worn tires with the marking still qualify on paper, but the checkpoint is not the place to learn they have no grip left.
Subaru, RAV4, Tesla and other common cases
AWD crossovers (Subaru, RAV4, CR-V, Forester, Outback). On M+S all-seasons you are exempt at R-1 and R-2 and must carry chains. Buy chains sized for your tires before the season and check your owner's manual: many AWD makers allow chains on one axle only, and the wrong axle can damage the drivetrain.
Teslas and other EVs. The rule is the same: AWD with snow-tread tires is exempt at R-1 and R-2, not R-3. Wheel-well clearance is tight on many EVs, so a standard chain may not fit. Manufacturers list an approved chain or low-profile traction device for each model; buy that one and practice once at home.
4WD pickups and SUVs. Part-time 4WD counts as four-wheel drive, so have it engaged. The same all-four-snow-tires rule applies, and a truck over 6,000 pounds gross weight does not qualify for the R-1 snow-tire exemption. If you are towing, the trailer rules apply: chains on one drive axle of the tow vehicle, and on at least one axle of a trailer with brakes.
Rental cars. Caltrans does not exempt rentals. An AWD rental on M+S tires clears R-1 and R-2; a 2WD compact on all-seasons clears R-1 only.
Why "carry chains" is not optional
The exemption is conditional on having chains with you. At the checkpoint you can be asked to show them, and drivers without chains are turned around. The second reason is the storm itself: R-2 can become R-3 while you are on the hill, and the way home may then require chains on every vehicle. Keep the chains in the car all winter, not in the garage.
Which chains fit
Chains are sized to the tire, so read the size off the sidewall (for example 225/65R17) and buy a set that lists it. Cars with limited clearance need low-profile chains or cable-style chains; the owner's manual says which type is allowed. Cable chains count as traction devices under California's rules and are easier to fit, but they wear faster on bare pavement. See how to put on chains for installation, the 25 to 30 mph speed limit and how chain installers work.
The answer for your car, live
Every Snowy Roads destination page, such as I-80, US-50 or Palisades Tahoe, shows the current level at each checkpoint. In the Snowy Roads iOS app you tell it whether you drive 2WD, AWD or 4WD and whether you have snow tires, and it answers "chains required" or "exempt, carry chains" for your vehicle at every checkpoint, then alerts you when that changes. Requirements change without notice as the storm moves; the official sources are Caltrans QuickMap (quickmap.dot.ca.gov) and 1-800-427-7623. Always carry chains.
FAQ
Does AWD get me out of chains at R-2?
Only with snow-tread tires (M+S, M/S, MS or the mountain snowflake symbol) on all four wheels, and only if you are carrying chains. AWD on unmarked tires needs chains at R-2.
Are all-season tires snow tires for chain control?
If the sidewall says M+S, M/S or MS, yes, they meet the California definition of a snow-tread tire. Summer tires with no marking do not.
Do I need chains on a Tesla?
The same rules apply as to any AWD car: exempt at R-1 and R-2 with snow-tread tires on all four wheels, chains at R-3, and chains in the car at all times. Use the traction device the manufacturer lists for your model, because clearance is tight.
Which wheels do the chains go on with AWD?
Whatever axle your owner's manual specifies. Many AWD vehicles take chains on one axle only, and some models require a specific low-profile type.
Do I have to show my chains at the checkpoint?
You may be asked to. Being able to open the trunk and point to them is the fastest way through; without chains you can be turned around even in an exempt vehicle.
Is a 4WD truck exempt at R-1 without snow tires?
No. The R-1 exemption is about tires, not drivetrain: it applies to passenger vehicles and light-duty trucks under 6,000 pounds with snow-tread tires on the drive wheels.