How many tires have to be chained on a semi?

It depends on the state and your setup. Colorado wants chains on at least 4 drive tires. Oregon wants 4 drive tires on a single drive axle truck that pulls a semitrailer, plus 2 trailer tires. Washington wants one tire on each side of a drive axle plus one trailer tire on many combinations. Nevada wants chains on at least 2 driving wheels, plus the braking wheels of a trailer that has brakes. Wyoming wants 2 drive wheels at opposite ends of one drive axle. Montana wants the driver wheels of one axle. Idaho wants one tire on each side of one drive axle and one rear axle on each towed vehicle. Check the rule for your truck.

Do trailers need chains?

Colorado says no. Washington wants one tire chained on the last axle of the last trailer. Oregon wants 2 tires chained on a semitrailer axle, one on each side. Nevada wants chains on the braking wheels of a trailing vehicle that has brakes. Idaho wants one tire on each side of one rear axle on each towed vehicle.

Can I use cables, AutoSocks or automatic chains instead of chains?

Some devices count. Colorado accepts the traction devices on CDOT's approved list, drive wheel sanders and pneumatic chains. Cables can cover 2 tires on one drive axle if chains are on the 2 outside tires of the other drive axle. Washington counts a device that the State Patrol lists as approved, but plastic chains are not allowed. Nevada allows a mechanical chain device on the drive axles if its cross members reach across at least 85 percent of the tire width.

When can I take my chains off?

Follow the signs and the state's notices. In Colorado, the chain law stays on until CDOT says it has ended, or until the center line or lanes are visible on a downhill grade. Take them off only in a safe place.

How much is the fine for not chaining up?

Colorado says not carrying chains on the named roads from September 1 to May 31 is a $100 or higher fine plus a $32 surcharge. Other winter driving violations are up to $500 plus a $78 surcharge, and $1,000 plus a $156 surcharge if you block the road. Oregon calls ignoring chain signs a class C traffic infraction, and says commercial drivers can face a class A violation. Montana sets $250, or $750 if the violation closes all lanes in one or both directions. Wyoming sets up to $250, or up to $750 if it closes the highway. We did not read the fine amounts for Washington, Nevada or Oregon, and the Idaho part we read gives none.

What if my state is not on this page?

We have read 7 states so far and add more in batches. A state that is missing has not been checked yet. It does not mean there is no chain rule. California has one. Its Vehicle Code bars driving on a signed section without traction devices, and Caltrans sets the control levels. Read the signs and the state's rule before you rely on this page.

Truck Chain Laws by State

Which trucks must carry and use chains, which tires get them, and where to read each rule. Made for drivers who cross the mountains.

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QUICK ANSWER

Do truck drivers have to use tire chains?

In the mountain states, a heavy truck must put on chains when the signs say so. We have read the rules in 7 states so far. Colorado, Montana and Washington also make trucks carry chains in winter on named roads. Idaho, Nevada, Oregon and Wyoming require chains when signs are posted. The weight line is 10,000 pounds in Nevada, Oregon and Washington, 16,001 pounds in Colorado, and 26,001 pounds in Montana. We read each rule on October 16 and 21, 2026.

States read so far: 7
Must carry in winter: 3
Required when signed: 4
Not checked yet: 43

Checked against each rule on October 16 and 21, 2026. This is a guide, not legal advice. The posted sign is what you must follow. Rules change, so read the rule linked in each card before you rely on it.

Truck chain rules side by side

This table lists the 7 states we have read so far. Pick a state to jump to the details below. 43 more states are not checked yet and are listed further down.

Truck chain rules by state, checked October 16 and 21, 2026
State	Trucks covered	Rule
Colorado	A commercial vehicle with a weight rating of 16,001 pounds or more that is used in commerce. This includes motorhomes at that weight, and vehicles that carry 16 or more people.	Must carry in winter
Idaho	All commercial vehicles as the law defines them in section 49-123(2)(d). We did not read that definition. Exempt: school buses, farm trucks, vehicles hauling farm products at any time of year, U.S. mail, forest products including chip trucks, mine products such as sand and gravel (not petroleum), wreckers and ITD maintenance vehicles.	Required when signed
Montana	A motor truck of 26,001 pounds GVW or more that tows a trailer must carry chains or an approved traction device. When chains are required, every vehicle towing a trailer must chain. A four-wheel-drive vehicle is exempt from the carry rule.	Must carry in winter
Nevada	A motor vehicle or combination with a gross weight of more than 10,000 pounds needs tire chains. A vehicle of 10,000 pounds or less may use traction devices, chains or snow tires.	Required when signed
Oregon	Medium duty vehicles, rated over 10,000 and under 26,001 pounds. Solo commercial vehicles, rated 26,001 pounds or more and not towing. Commercial vehicles rated 26,001 pounds or more that tow a trailer.	Required when signed
Washington	Vehicles and combinations over 10,000 pounds gross vehicle weight rating (GVWR). Snow removal vehicles of the state DOT are exempt.	Must carry in winter
Wyoming	Operators of commercial vehicles. The law gives no weight line in the section we read.	Required when signed

States that make trucks carry chains in winter

In these states the rule names roads where a truck must carry chains during a set season. Chains must also go on when the signs say so.

Colorado

Must carry in winter

Which trucks: A commercial vehicle with a weight rating of 16,001 pounds or more that is used in commerce. This includes motorhomes at that weight, and vehicles that carry 16 or more people.
When: You must carry chains or an approved traction device from September 1 to May 31 on the roads below. The chain law itself is in effect when CDOT announces it on signs, message boards and its travel site. It ends when CDOT says so, or when the center line or lanes are visible on a downhill grade.
Which tires get chains: Chains or approved traction devices on at least 4 drive tires. If the truck has fewer than 4 drive tires, chain all of them. Buses chain 2 drive tires. Straight trucks, single drive axle and tandem drive axle combinations and auto transporters chain 4.
What to carry: Chains must be real chains with nine or more cross chains. Clip-on chains are not allowed. Approved traction devices on CDOT's list, drive wheel sanders and pneumatic chains also count. Tire cables may cover 2 tires on one drive axle if chains are on the 2 outside tires of the other drive axle. You cannot use AutoSocks and cables together.
Roads named in the rule: I-70 west of milepost 259 (Morrison), CO 9 from milepost 63 to 97 (Frisco to Fairplay), US 40 west of milepost 256 (Empire), US 50 west of milepost 225 (Salida), US 160 west of milepost 304 (Walsenburg), US 285 west of milepost 250 (Morrison) and US 550 from milepost 0 to 130.
Fines: Not carrying chains on those roads from September 1 to May 31 is a $100 or higher fine plus a $32 surcharge, says CDOT. For other winter driving violations, CDOT lists up to $500 plus a $78 surcharge. If you are stuck and block the road, the fine is $1,000 plus a $156 surcharge.
Good to know: Trailers do not need chains. Placarded hazmat trucks must follow the chain law. They may pass the chain-up signs and chain up on a safe spot off the traveled road where it is covered with snow or ice. While the chain law is active, trucks stay in the right lane unless they must pass a stalled or slow vehicle. CDOT says a 2024 update (Senate Bill 24-100) expanded the must-carry law to more roads, starting September 1, 2024.

CDOT Chain Up Tips and Senate Bill 24-100 Senate Bill 24-100 (signed text)

Montana

Must carry in winter

Which trucks: A motor truck of 26,001 pounds GVW or more that tows a trailer must carry chains or an approved traction device. When chains are required, every vehicle towing a trailer must chain. A four-wheel-drive vehicle is exempt from the carry rule.
When: From October 1 through April 30 you must carry them on a mountain pass or a similar stretch the state names. The Department of Transportation (MDT) can also decide at any time of year that conditions are dangerous and require chains in marked areas.
Which tires get chains: Chains on the driver wheels of one axle for a vehicle that tows a trailer, MDT says.
What to carry: Approved traction control devices set by MDT. MDT says AutoSocks are an approved alternative to chains.
Roads named in the rule: MDT lists the places. They include I-90 at Lookout Pass, Homestake Pass and Bozeman Hill, US-12 at Lolo Pass and MacDonald Pass, US-2 at Marias Pass, and US-93 at Lost Trail Pass.
Fines: Not carrying the device: $225 for a first offense, $225 to $500 for a later one. Not using chains when required: $250, or $750 if the violation closes all lanes in one or both directions.
Good to know: Signs mark chain-up and chain-removal areas.

MCA 61-9-406, 61-9-436 and 61-9-520 MDT: Montana Tire and Chain Laws

Washington

Must carry in winter

Which trucks: Vehicles and combinations over 10,000 pounds gross vehicle weight rating (GVWR). Snow removal vehicles of the state DOT are exempt.
When: When signs marked "chains required" are posted, you may not enter the area without chains on. On the roads below you must carry enough chains from November 1 to April 1, and at other times when chains are required.
Which tires get chains: Two to four axles, single drive axle: one tire on each side of the drive axle. Dual drive axles: one tire on each side of one drive axle. If you pull a trailer, add one tire on the last axle of the last trailer. Five axles with dual drive axles and a tandem trailer: at least 4 tires on the drive axles, plus one trailer tire. Some five-axle combinations and all combinations with 6 or more axles need every tire on a drive axle chained. The rule lists each type.
What to carry: Every vehicle over 10,000 pounds must carry at least 2 extra chains. Each chain needs two side chains with hardened metal cross chains, so at least one cross chain touches the road at all times. Plastic chains are not allowed. If you use automatic chains, also carry regular chains for the outside tires of each axle that has them. An alternative traction device that the State Patrol lists as approved counts as chained.
Roads named in the rule: I-90 from North Bend to Ellensburg, I-82 from Ellensburg to Selah, SR 2 from Dryden to Index, SR 12 from Packwood to Naches, SR 410 from Enumclaw to Naches, two sections of SR 20, and sections of SR 14, SR 97, SR 155, SR 542 and SR 970.
Good to know: Trucks making local deliveries shown on the bill of lading, and not crossing the pass, are exempt from the carry rule when they are outside a chain required area. The state DOT or State Patrol may also keep out any vehicle that will have trouble in the area.

WAC 204-24-050

States that require chains when signs are posted

In these states the rule applies when the state posts signs or announces a chain requirement. Read the signs on the road, and keep chains in the truck.

Idaho

Required when signed

Which trucks: All commercial vehicles as the law defines them in section 49-123(2)(d). We did not read that definition. Exempt: school buses, farm trucks, vehicles hauling farm products at any time of year, U.S. mail, forest products including chip trucks, mine products such as sand and gravel (not petroleum), wreckers and ITD maintenance vehicles.
When: Only when the Idaho Transportation Department (ITD) decides that Lookout Pass or Fourth of July Pass on I-90, or Lolo Pass on Highway 12, is unsafe without chains. ITD must give several advance notices, room to pull out, and notice at a safe pull-out point before the chains are required. It may not post a chain requirement on bare pavement.
Which tires get chains: One tire on each side of one drive axle, whatever the number of drive axles. Also one tire on each side of one axle at or near the rear of each towed vehicle. That axle may not be a variable load suspension axle or a converter dolly axle.
What to carry: Chains as defined in section 49-104. Another traction device that gives equal or better traction may be used.
Roads named in the rule: Lookout Pass and Fourth of July Pass on I-90. Lolo Pass on state highway 12.
Good to know: ITD puts up signs that show the chain requirement. The law gives no fine in the part we read.

Idaho Code § 49-948(5) to (9)

We read this on FindLaw's copy of the Idaho Code, current as of January 1, 2024. Check the state rule for the latest text.

Nevada

Required when signed

Which trucks: A motor vehicle or combination with a gross weight of more than 10,000 pounds needs tire chains. A vehicle of 10,000 pounds or less may use traction devices, chains or snow tires.
When: When a highway is marked or posted with signs that require traction devices, tire chains or snow tires, and the road is icy or snowy. Some signs require traction devices or chains on all vehicles except four-wheel drive vehicles with snow tires on all wheels.
Which tires get chains: On at least 2 driving wheels of the motor vehicle, and on the braking wheels of any trailing vehicle in the combination if that vehicle has brakes or is required to have them.
What to carry: The sections we read apply when the highway is marked or posted. A mechanical device that drops a chain of metal cross members under the tire while you drive is allowed if the cross members reach across at least 85 percent of the tire width. It may be used only on drive axles, and it must be on both sides of the vehicle.
Good to know: The law does not make an exception for emergency vehicles.

NRS 484D.515 to 484D.530

Oregon

Required when signed

Which trucks: Medium duty vehicles, rated over 10,000 and under 26,001 pounds. Solo commercial vehicles, rated 26,001 pounds or more and not towing. Commercial vehicles rated 26,001 pounds or more that tow a trailer.
When: When signs say chains are required. ODOT says traction tires may replace chains only on vehicles rated 10,000 pounds or less that are not towing. Trucks over 10,000 pounds must use chains. In a conditional closure, chains can be required on all vehicles, whatever the tires.
Which tires get chains: Single drive axle, solo or medium duty: one tire on each side of the drive axle. Tandem drive axle: 2 tires on each side of the main drive axle, or one tire on each side of each drive axle if both are powered. A single drive axle truck pulling a semitrailer: 2 tires on each side of the drive axle, plus one tire on each side of any semitrailer axle. A tandem drive truck pulling a semitrailer: the drive axle chains above, plus one tire on each side of any semitrailer axle.
What to carry: ODOT says chains must be in or on your vehicle, the right size, and enough of them to meet the placement rules.
Fines: ODOT says ignoring chain signs is a class C traffic infraction. It also says commercial drivers who do not carry and use chains may face a class A traffic violation. We did not read the fine amounts.
Good to know: The rule also lists trailers, truck and trailer combinations, and B-train and C-train doubles. Check the rule for your setup. For questions about commercial vehicles, ODOT suggests that you call your local Port of Entry.

OAR 734-017-0010 ODOT: Chains and traction tires

We read this on Cornell Law School's copy of the rule, checked against ODOT's chains and traction tires page. Check the state rule for the latest text.

Wyoming

Required when signed

Which trucks: Operators of commercial vehicles. The law gives no weight line in the section we read.
When: When the highway patrol or WYDOT decides travel is hazardous and signs are up, including temporary or electronic signs. In extremely hazardous conditions, travel is limited to vehicles with tire chains, all-wheel-drive vehicles with adequate mud and snow or all-weather tires, and emergency vehicles. A commercial vehicle must use chains when chains are required.
Which tires get chains: At least 2 of the drive wheels, at opposite ends of the same drive axle.
What to carry: Tire chains are metal chains with two loops, one on each side of the tire, joined by at least 9 evenly spaced chains across the tread. Other traction devices that give equal or better traction also count.
Fines: Up to $250 for breaking the restriction. Up to $750 if the violation closes all lanes in one or both directions.
Good to know: There is no fixed season. Do not stop in the driving lane to put on or take off chains, WYDOT says.

W.S. 31-5-956 WYDOT: Wyoming's chain law

States we have not checked yet

We add states in batches. A state on this list has not been read yet. That does not mean it has no chain rule. Follow the posted signs and check the state's rule before you rely on this page.

California is the one many drivers ask about. Its Vehicle Code bars driving on a section of highway that is signed for traction devices unless you have them (Cal. Veh. Code § 27459). We could not read Caltrans' chain control levels for trucks yet, so California is not on the cards above.

Alabama, Alaska, Arizona, Arkansas, California, Connecticut, Delaware, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, West Virginia, Wisconsin.

How we checked these rules

We read each state's own rule or its highway department page. Each card links to them.
We give a fine only where we read it. Montana and Wyoming state theirs in the law. For Washington and Nevada we did not read the penalty sections, and the Idaho part we read gives none, so we give none.
Oregon's rule was read on Cornell Law School's copy and checked against ODOT's page. Idaho's was read on FindLaw's copy of the Idaho Code.
Weight lines differ. Colorado starts at 16,001 pounds. Montana starts at 26,001 pounds for a truck that tows a trailer. Nevada, Oregon and Washington start above 10,000 pounds. Idaho and Wyoming name commercial vehicles without a weight in the parts we read. Check the rating on your truck's plate.
Last checked October 16 and 21, 2026. States change these rules. Tell us if you see one that is out of date.

Free tools for winter trips

Corridor weather alerts

Check the weather on the roads you run before you leave.

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Hours of service trip planner

Chaining up and slow roads use up your hours. Plan the day.

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Truck parking finder

Find a place to park when a pass closes or chains are required.

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Low bridge lookup

Check known low bridges on a detour before you take it.

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More trucking rules by state

CHAIN LAW FAQ

Truck chain law questions

Short answers to what drivers ask most about tire chains.

Get a dispatcher who plans your winter trips and your drive time

It depends on the state. In Colorado, a commercial vehicle of 16,001 pounds or more must carry chains from September 1 to May 31 on named roads. In Washington, every vehicle over 10,000 pounds must carry at least 2 extra chains, and must carry enough chains on named roads from November 1 to April 1. In Montana, a motor truck of 26,001 pounds or more that tows a trailer must carry chains from October 1 to April 30 on named passes. In Oregon, chains must be in or on the truck when signs require them. In Idaho, Nevada and Wyoming, the rule applies when the road is signed.