Montana Tire Chain Laws

How Montana handles chains

$250 is the fine for skipping chains when MDT posts the order, and $750 if you close all lanes (MCA 61-9-520). From October 1 to April 30, trucks 26,001 pounds and up towing a trailer must carry chains on designated passes (MCA 61-9-436). When the signs and flashing beacons go up on passes like Lookout on I-90, US-2 Marias, US-12, US-93, and I-15, chain the driver wheels of one axle if you tow a trailer of any weight. AutoSock is an approved alternative. Four-wheel drive is exempt only from the carry rule. Check MDT 511.

When, where, and what counts

• When required: MDT can post a chain or traction requirement at any time of year, and chains go on only when it does. From October 1 to April 30, motor trucks 26,001 pounds GVW and up towing a trailer must also carry chains or an approved traction device while on a designated pass or similar stretch (MCA 61-9-436). MDT shows an active requirement with signs that have flashing beacons and with signs that flip open.
• Where: Designated passes and corridors including Lookout Pass on I-90, I-15, US-93, US-12, and US-2 over Marias Pass, among nearly 30 posted locations across the state. Many apply in one direction only, such as Lookout Pass westbound and Marias Pass eastbound.
• Applies to: Vehicles towing a trailer (towing units) of any weight when MDT posts a chain requirement. The October 1 to April 30 carry rule covers only motor trucks 26,001 pounds GVW and up towing a trailer, and four-wheel-drive vehicles are exempt from that carry rule.
• Chains vs traction devices: When MDT posts the order, a vehicle towing a trailer chains the driver wheels of one axle. AutoSock is an approved alternative to tire chains. Four-wheel-drive vehicles are exempt only from the October 1 to April 30 carry rule. At a posted requirement a four-wheel-drive towing unit follows the signs, which may set separate rules for four-wheel drive in gear (MCA 61-9-406(7)). Snow tires alone do not satisfy a posted chain requirement.
• Check the live order: MDT 511 (511mt.net, the MDT 511 app, or dial 511; call 800-226-7623 from outside Montana or if 511 does not work on your carrier) for the active chain order; flashing beacons and signs at designated passes show when chains are required.
• Fine: $250 for failing to use chains or an approved traction device when MDT posts the requirement, and $750 when the violation causes the closure of all lanes in one or both directions of a highway. It is a nonmoving offense, not a misdemeanor (MCA 61-9-520). Failing to carry traction devices under the October 1 to April 30 carry rule is $225 for a first offense and $225 to $500 for later offenses (MCA 61-9-436).

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