Chain Laws by State for Truckers: Western States Guide

Winter driving in the West

Updated September 27, 2026

Several western states make big trucks put on chains when the signs say so, and some make you carry chains all winter. The rules differ by state: who they cover, how many tires to chain, and when.

Check each state’s rule before you cross it. This guide sums up nine western states, each sourced to that state’s own page, and links to the site that shows today’s road status.

Is a chain law on right now? This page explains the rules. For today’s roads, use the state road sites in how to check before you go, and watch the signs on your route.

9Western states in this guide

Oct 1Montana carry season starts, runs to Apr 30

Nov 1Washington carry season starts, runs to Apr 1

10,000 lbChain line in Oregon, Washington and Nevada

Our home base is in the Denver area, and our drivers run rail-head and regional freight across the Rocky Mountain region. Here is what each western state asks of a truck driver in winter, and how to stay safe once the snow starts.

Chain Laws by State

Here are the commercial truck rules at a glance. Each row sums up the state’s own page. Tap a state name to jump to its details, and read them before you count on any one line.

Commercial truck chain rules in nine western states. Every row checked September 27, 2026.
State	Trucks covered	Must carry chains	When chains go on	Source
Wyoming	Commercial vehicles (no weight line stated)	No set season	Level 2 restriction posted: at least 2 drive wheels on the same axle	WYDOT
California	Over 6,500 lb gross	No set dates	Chain signs posted: chains on the drive axle	Caltrans
Oregon	Over 10,000 lb GVW, or towing	When signs say so	Chain signs posted: drive tires plus one trailer axle	ODOT TripCheck
Washington	Over 10,000 lb GVWR	Nov 1 to Apr 1 on 12 listed routes	Chain signs posted: drive tires plus one trailer tire	WAC 204-24-050
Utah	12,000 lb GVWR or more	No set season	Traction restriction posted: all rear drive tires, one per dual pair	Utah Rule R920-6
Idaho	Over 26,000 lb	No set season	Posted on 3 named passes: one drive axle plus each trailer	Idaho Code 49-948
Montana	Carry rule: 26,001 lb GVW or more, towing	Oct 1 to Apr 30 on listed passes	Chain signs posted: drive wheels of one axle	MDT
Nevada	Over 10,000 lb	No season found	Signs posted: 2 drive wheels, 2 trailer braking wheels	NRS 484D
Colorado	Over 16,000 lb, used in commerce	Sep 1 to May 31 on 7 routes	When the Commercial Vehicle Chain Law is in effect	Our Colorado guide

Rules change, and state pages do not always agree with each other. Where we found two official versions, the details below say so. The state’s current rule is the one that counts.

State-by-State Details

Wyoming Chain Law

Wyoming has two levels of restriction, set on stretches of highway when conditions call for it. Under Level 1, you need chains, good snow tires or all-wheel drive. Under Level 2, commercial vehicles must chain at least two drive wheels at opposite ends of the same drive axle.

The rule starts when signs go up. Other traction devices count if they grip at least as well as metal chains. As of September 2026, state law sets fines of up to $250 for breaking a restriction, and up to $750 if it leads to a road closure. WYDOT also says: never stop in the driving lane to put chains on or take them off.

California Chain Law

California has no set dates for carrying chains. When chain signs are posted, every heavy-duty vehicle over 6,500 pounds gross must have chains mounted to go on. Snow tires do not exempt a truck. Caltrans may stop trucks to check for chains and send trucks without them back to lower ground.

Chains go on the drive axle. A semi-trailer needs only one set, however many axles it has.
With super single tires, chain every drive wheel. The tag axle needs none.
Caltrans and the CHP may require chains on all drive wheels when conditions are bad.
The speed limit with chains required is 25 or 30 mph.

Cable chains and other traction devices are allowed but may be restricted at times. On Donner Pass, Caltrans says heavy trucks usually need link chains on at least the main drive axle. Caltrans says you can be cited and fined, but its pages list no dollar amount.

Oregon Chain Law

Oregon’s chain law covers every highway in the state. There are no set dates. Signs tell you when chains must be carried and when they must be used. When chains are required, they go on vehicles over 10,000 pounds GVW and on any vehicle towing.

Oregon’s rule for a tractor with a semi-trailer:

Tandem drive: two tires on each side of the main drive axle, or one tire on each side of each drive axle if both axles are powered.
Trailer: two tires, one on each side, of any semi-trailer axle.
Dual wheels: the chain may go on the inside or outside tire.

Oregon may also post tighter rules on some passes, such as I-5 over the Siskiyous. A commercial driver who fails to carry and use chains can get a Class A traffic violation.

Washington Chain Law

Washington is the one state in this guide with a line written for car haulers. Its rule calls them “automobile transporters.” When chain signs are posted:

Single drive axle: chain one tire on each side of the drive axle.
Dual drive axles: chain one tire on each side of each drive axle.
Trailer: chain one tire on the last axle of the last trailer. With tandem rear axles, either of the last two axles works.

Every vehicle over 10,000 pounds GVWR must carry at least two extra chains. From November 1 to April 1, those trucks must carry enough chains on 12 listed routes, including I-90 from North Bend to Ellensburg. Plastic chains are not allowed. The State Patrol’s approved device list, updated September 2026, includes AutoSock for heavy vehicles.

Official sources differ. WSDOT’s chain diagram describes five-axle car haulers a little differently from the written rule, and its route list does not match the rule on three routes. We follow the rule, WAC 204-24-050. Check both before you run Washington passes.

Loaded car hauler on a winding two-lane road with mountains behind it at dusk

Utah Chain Law

Utah uses a traction law. UDOT marks traction segments and can require devices on vehicles of 12,000 pounds GVWR or more. A tractor-trailer puts devices on all rear drive tires, but only one tire of each dual pair. Chains, studs and snow socks all count. The rule also allows all-wheel or four-wheel drive with snow-rated tires.

UDOT can set a restriction up to 24 hours before a storm, and on the worst segments it can keep trucks off even if they are equipped. Breaking the rule is a citable infraction.

Official sources differ. One of UDOT’s own truck pages still describes an older version of this rule. We follow the current rule, R920-6.

Idaho Chain Law

Idaho’s truck chain law covers three passes: Lookout Pass and Fourth of July Pass on I-90, and Lolo Pass on US 12. It applies to commercial vehicles over 26,000 pounds. When chains are posted, chain at least one tire on each side of one drive axle. Also chain one tire on each side of an axle at or near the rear of each trailer. Other devices count if they grip as well as chains, and the state may not post chains on bare pavement.

Montana Chain Law

From October 1 to April 30, a truck of 26,001 pounds GVW or more that is towing a trailer must carry traction devices on mountain passes the state marks. Four-wheel drive vehicles are exempt from the carry rule. MDT lists 17 places where chains may be required, including Homestake Pass and Lookout Pass on I-90 and Marias Pass on US 2.

When “chains required” signs are up, chain the drive wheels of one axle. MDT can require chains at any time of year, and it approves AutoSocks. As of September 2026, state fines are $225 for a first offense of not carrying devices, and $250 for not using chains. That goes to $750 if it closes the road.

Nevada Chain Law

In Nevada, when signs require chains, vehicles over 10,000 pounds must use tire chains. Chains go on at least two drive wheels, and on at least two braking wheels of any trailer that has brakes. Nevada also approves some fabric and plastic traction devices.

Around Lake Tahoe, on Mt. Rose Highway, Kingsbury Grade and US 50 into Carson City, only vehicles with chains, or four-wheel drive with snow tires, may go on when chains are posted. NDOT and the Highway Patrol can keep any vehicle out of a chain control area.

Colorado Chain Law

Colorado has the longest carry season of the states in this guide, and a line of its own for auto transporters. We cover it in detail in our Colorado chain law guide for truckers: the routes, the dates, the fines, and how to chain up a car hauler.

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How to Check Chain Law Status Before You Go

No guide can tell you whether chains are on today. Check the state’s own road site for your whole route before you leave, not only the first pass. Most states also answer by phone at 511.

WyomingNo set seasonWYOroad.info
CaliforniaNo set datesCaltrans QuickMap or 800-427-7623
OregonCarry when signedTripCheck.com
WashingtonCarry Nov 1 to Apr 1WSDOT mountain pass reports
UtahNo set seasonUDOT Traffic
IdahoThree named passesIdaho 511
MontanaCarry Oct 1 to Apr 30Montana 511
NevadaNo season foundNVroads.com
ColoradoCarry Sep 1 to May 31COtrip.org

Winter Driving Tips for Truck Drivers

Start with the federal rule. Under 49 CFR 392.14, you must use extreme caution when snow, ice, sleet, fog or other conditions hurt your visibility or traction. You must slow down. If it gets dangerous enough, you must stop, and not go on until you can drive safely.

The tips below are practical advice from the road, not rules:

Check your chains before the season. Count them, look for broken links and worn cross chains, and carry spares. Washington requires two extra.
Practice in the yard. Learn to chain your own rig on dry ground in daylight, not on a dark pass in blowing snow.
Check the whole route. Look at every state road site on your trip before you roll, and again at each stop.
Chain up in the right place. Use chain-up areas and pull-outs. Never stop in a travel lane to put chains on.
Slow down and add space. Keep a long gap, brake early and gently, and slow down before curves, not in them.
Know your equipment. On a car hauler, know where your chains sit near your hydraulic lines before you need them.
Do a real pre-trip. Winter is hard on air lines, lights and tires. Our pre-trip inspection checklist covers the walkaround.

When Weather Eats Your Hours

Federal hours-of-service rules have a narrow exception for bad weather. Under 49 CFR 395.1(b), if you hit adverse driving conditions you could not have known about before your day or your break, you may drive up to two extra hours. That time is only to finish the run or to reach a safe place.

A forecast storm you knew about does not count. Our guide to hours of service for car haulers explains the exception in full.

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Chain Law FAQs

Which states have chain laws for trucks?

In the West, Wyoming, California, Oregon, Washington, Utah, Idaho, Montana, Nevada and Colorado all have rules for when trucks must chain up or use traction devices. The rules differ on weight, tires and dates, so check each state’s own page.

When do truckers have to carry chains?

It depends on the state. Colorado’s carry season runs September 1 to May 31, Montana’s October 1 to April 30, and Washington’s November 1 to April 1, each on listed routes. The other states in this guide set no season and require chains when signs are posted.

How many tires do I have to chain on a semi?

Each state sets its own count. Wyoming requires at least two drive wheels on the same axle. Washington requires at least four drive tires on a standard five-axle rig, plus one trailer tire. Read the state’s rule for your axle setup.

Can I use AutoSocks instead of chains?

In some states. Montana approves AutoSocks, Washington’s State Patrol lists AutoSock for heavy vehicles, and Utah counts snow socks. California and Nevada allow some devices but may restrict them. Check the state’s current list.

How do I know if a chain law is in effect today?

Check the state’s road condition site or call 511, and watch the signs on your route. Each state posts chain and traction restrictions on signs and on its road site.

Sources

Last checked September 27, 2026. Chain laws change, and some state pages disagree with each other. Confirm the current rules with each state before you drive. This guide is a plain-language summary, not legal advice.