Chain laws for truckers: California, Colorado, Washington and Oregon

Chain season is here. If you run west this winter, the rules for heavy trucks are stricter than for cars, and they change from state to state. Here is a short, practical guide to the four states most drivers ask us about, with links to the official pages.

Fact-checked on October 27, 2026, against official state transportation guidance and rules. Rules and signs change – always follow posted signs and officers on scene. This is not legal advice.

What “chain control” means

When snow or ice hits a mountain route, the state posts chain controls: signs, message boards and checkpoints that tell you which vehicles must chain up before they go on. Some states also require trucks to carry chains during the season, even on a dry day. Two questions to ask in every state: do I have to carry chains, and when do I have to put them on?

California: R-1, R-2 and R-3

California does not have fixed dates for carrying chains. When a road is posted for chains, heavy-duty vehicles over 6,500 pounds gross weight must have chains mounted to proceed. Caltrans uses three levels:

  • R-1: chains required, except for passenger vehicles and light trucks under 6,000 pounds gross weight with snow tires on at least two drive wheels. Exempt vehicles must still carry chains. Vehicles towing trailers must have chains on one drive axle, and trailers with brakes must have chains on at least one axle.
  • R-2: chains or traction devices required. Caltrans’ truck guidance limits the four-wheel or all-wheel drive exemption to vehicles under 6,500 pounds gross weight with snow tires on all four wheels, and exempt vehicles must still carry chains.
  • R-3: chains or traction devices required on all vehicles, no exceptions. A highway is often closed before an R-3 condition is imposed.

Chains are most often required on I-5 north of Redding, I-80 over Donner Pass and US 50 over Echo Summit, and sometimes on SR-58 near Tehachapi, I-15 over Cajon Pass and I-5 over Tejon Pass. Automatic traction devices are legal, but trucks with only ATDs may have to add chains on outside wheels. Follow the signs and the instructions of Caltrans or CHP at chain checkpoints, even if they differ from what you heard on the radio.

Colorado: the Must Carry law

From September 1 through May 31, commercial motor vehicles with a GVWR or GCWR of 16,001 pounds or more must carry chains or approved alternative traction devices on these mountain corridors:

  • I-70 west of MP 259 (Morrison)
  • CO-9 from MP 63 to MP 97 (Frisco to Fairplay)
  • US 40 west of MP 256 (Empire)
  • US 50 west of MP 225 (Salida)
  • US 160 west of MP 304 (Walsenburg)
  • US 285 west of MP 250 (Morrison)
  • US 550 from MP 0 to MP 130

The expanded routes first fell under the seasonal carry rule on September 1, 2024; before that, it covered only I-70 between Dotsero and Morrison. When the Commercial Vehicle Chain Law is in effect, a truck needs chains or approved traction devices on at least four drive wheel tires (all drive tires if it has fewer than four). Clip-on chains are not allowed. CDOT announces chain law by mile point and exit number on message signs, its website and alerts.

Washington: carry chains November 1 – April 1

On listed mountain routes, vehicles and combinations over 10,000 pounds gross vehicle weight rating must carry sufficient chains from November 1 to April 1, whatever the weather. Qualifying local deliveries that stay outside chain-required areas and do not cross the pass are exempt from this seasonal rule. Trucks over that rating must also carry at least two extra chains in case conditions get worse or a chain breaks. From April 2 to October 31, chains must be carried where posted – and always follow posted chain-up requirements. Listed routes include I-90 from North Bend (MP 32) to Ellensburg (MP 101), I-82 from Ellensburg to Selah, SR-2 from Dryden to Index, SR-12 from Packwood to Naches and SR-410 from Enumclaw to Naches, among others.

Conventional chains need two side chains and hardened metal cross chains. Plastic chains are not allowed; cable chains must meet Washington’s equipment standards, and alternative traction devices must be approved for your vehicle type. Hauling oversize? When “Traction Advisory/Oversized Vehicles Prohibited” is displayed, oversize permit moves over the pass are prohibited unless a specific exemption in WAC 468-38-075 applies.

Oregon: chain placement by vehicle

In Oregon, vehicles with a gross vehicle weight rating of 10,000 pounds or less may use traction tires instead of chains if they are neither towing nor being towed; separate exemptions apply to certain vehicles. Heavier vehicles must use chains when posted requirements apply to them, and in very bad conditions a “conditional closure” can require chains on every vehicle – the exact restrictions depend on the closure. How many tires you chain depends on your axle setup – solo commercial vehicles and combinations with trailers each have their own chart. For commercial chain-up questions, ODOT points drivers to the local Port of Entry.

Before you climb: a short checklist

  • Carry the right chains for your axle setup and the states on your route – and check them before the season, not at 2 AM on the shoulder.
  • Practice chaining up at home or at the yard.
  • Use a safe chain-up area outside the travel lane. Pull fully off the road, vest on, hazards on.
  • Check the pass before you get there, not at the bottom of the grade.
  • Know your limits. If a road is about to go to R-3 or close, no load is worth it.

Check ahead, not at the bottom of the pass

Check official state travel maps before you leave, and follow posted restrictions and officers’ instructions on the road. To see chain controls, closures and weather alerts along your whole route in one place, TruckRoute.AI shows live DOT alerts and official National Weather Service alerts before you hit the pass. Start with a 3-day free trial.

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