Chains, traction tires and studded tires: the rules state by state

• R1: chains on every vehicle except passenger cars and light trucks under 6,000 lb with snow tires on at least two drive wheels. Those must still carry chains.
• R2: chains or traction devices on every vehicle except four-wheel and all-wheel drive with snow-tread tires on all four wheels. Those must carry traction devices.
• R3: chains or traction devices on every vehicle, no exceptions. It is rare: the road usually closes first.

A snow-tread tire is one marked MS, M/S, M+S or MUD AND SNOW on the sidewall. Chain controls go up by area, from a checkpoint where Caltrans crews turn back cars without chains; the Highway Patrol can cite drivers who ignore them. Studded tires are legal from November 1 to April 30.

• Carry chains or traction tires: have them in the car; you may not need to fit them.
• Chains required on vehicles towing or with a single drive axle over 10,000 lb.
• Chains required on vehicles towing or over 10,000 lb.
• Chains required; traction tires allowed on vehicles under 10,000 lb.

Oregon's traction tires are studded tires or tires rated for severe snow (the mountain-snowflake symbol). All-wheel drive is exempt from chains when it is not towing, weighs 6,500 lb or less unloaded, has mud-and-snow, all-weather radial or traction tires on every wheel, drives both axles, and carries chains. Ignoring a chain requirement is an $800 fine. Studded tires are legal from November 1 to March 31; out of season the fine is close to $200.

• Traction tires advised: advice for cars; oversize loads may not travel.
• Traction tires required: every passenger vehicle needs approved traction tires; vehicles over 10,000 lb must chain.
• Chains required: every vehicle must chain, except four-wheel and all-wheel drive.
• Chains required on all vehicles: every vehicle chains up, all-wheel drive included.

An approved traction tire has at least 4/32" of tread and the mud-and-snow or mountain-snowflake marking. All-wheel drive is exempt from "chains required" only if it carries chains for one set of drive tires; studded tires never stand in for chains. Ignoring the signs costs $500. Studded tires are illegal from April 1 to November 1. In Mount Rainier National Park, every vehicle must carry chains from November 1 to May 1, four-wheel drive included.

• Passenger Vehicle Traction Law: four-wheel and all-wheel drive need tires rated M+S, all-weather or mountain-snowflake with at least 3/16" of tread; two-wheel drive needs chains or a traction device.
• Passenger Vehicle Chain Law: every vehicle needs chains or an approved traction device.
• On I-70 between Dotsero and Morrison, from September 1 to May 31, two-wheel-drive vehicles must carry chains or a traction device whatever their tires, and the Traction Law applies whenever CDOT calls it.

Fines: CDOT's traction-law page lists $100 plus a $33 surcharge, and $500 plus $157 if your car blocks a lane; a CDOT release of November 2025 gives $50 plus $17 for the Traction Law. The State Patrol enforces the law after a crash or a delay, not at random checks. Trucks of 16,001 lb or more must carry chains from September 1 to May 31 on I-70 and other mountain highways.

• Chain Law Level 1: chains, adequate snow tires, or all-wheel drive.
• Chain Law Level 2: chains, or all-wheel drive with mud-and-snow or all-weather tires. Commercial vehicles chain two drive wheels on the same axle.

Violating the restriction costs $250; $750 if it leads to the highway being closed.

• Chains or snow tires required: cars under 10,000 lb need snow tires or traction devices; four-wheel drive passes with four mud-and-snow tires.
• Chains required, except for: every vehicle except four-wheel drive with four mud-and-snow tires.

NDOT says Nevada does not use a "chains mandatory" level. A snow tire needs at least 3/16" of tread, and NDOT advises the mountain-snowflake symbol with the M+S marking. On Mount Rose Highway (SR-431), Kingsbury Grade (SR-207) and US-50 between Glenbrook and Carson City, only four-wheel and all-wheel drive with snow tires, or vehicles with chains, may travel when the restriction is up. NDOT advises snow tires from October 1 to April 30.

Under Utah's traction rule, a car complies with traction devices on two drive tires, or with all-wheel or four-wheel drive on M+S or mountain-snowflake tires; a two-wheel-drive car under 12,000 lb can also comply with mountain-snowflake tires. In Big and Little Cottonwood Canyons (SR-190 and SR-210), tires need at least 5/32" of tread. UDOT can put the rule in force 24 hours before a storm. Studded tires with tungsten carbide studs are legal from October 15 to March 31.

None of the four publishes chain levels for passenger cars like the states above. Montana's law lets its transportation department require tires, chains or traction devices by sign, with different rules for four-wheel drive. What they do set is when studded tires are legal:

• Idaho: October 1 to April 30.
• Montana: October 1 to May 31.
• Arizona: October 1 to May 1.
• Alaska: north of 60° latitude, illegal from May 1 to September 15; south of it (Homer, Kodiak, Southeast), from April 15 to September 30. Anchorage allows them from October 1.

• New York: October 16 to April 30.
• Pennsylvania: November 1 to April 15.
• West Virginia: November 1 to April 15.

No eastern state has a chain law for cars. Pennsylvania restricts trucks, buses, RVs and cars towing trailers in winter storms, and at its highest tier closes the road to every vehicle. Vermont's only mandatory chain-up area is VT-9 between Wilmington and Bennington, for vehicles over 26,000 lb.

Rules we could not confirm on an official page are not here: New Mexico's, Nevada's studded tire dates, the fines in California, Nevada, Utah and Montana, and Wyoming's studded tire dates. Commercial vehicle rules are summarized only where they touch the road you share. Each state's DOT is the authority; the sources are listed below.