Idaho Tire Chain Laws

How Idaho handles chains

The statute sets no chain-specific fine. A violation of the posted chain-up order is a standard Idaho traffic offense, and the court sets the amount (Idaho Code 49-948). There is no chain season. The order covers three passes: Lookout and Fourth of July on I-90, and Lolo on SH-12. It binds commercial vehicles over 26,000 pounds. Chain one tire each side of one drive axle. Watch Idaho 511.

When, where, and what counts

• When required: No fixed chain season. The October 1 to April 30 window is for studded tires, not chains. ITD activates chain-up only when a covered pass is unsafe, with advance signs and a safe pull-out point before the chain-up line.
• Where: The three passes named in the statute: Lookout Pass and Fourth of July Pass on I-90, and Lolo Pass on SH-12.
• Applies to: Commercial vehicles as Idaho Code defines them, meaning a gross vehicle or combination weight rating over 26,000 pounds, or a vehicle built to carry 16 or more people. School buses, farm, agricultural, mail, and forest and mining haulers are exempted by the statute.
• Chains vs traction devices: Chain a minimum of one tire on each side of one drive axle, whatever the number of drive axles, plus one axle at or near the rear of each towed vehicle. That rear axle cannot be a variable load suspension axle or an axle of a converter dolly. Chains go on in addition to pneumatic tires, so snow tires do not substitute. The statute does allow a substitute for chains themselves: any other traction device differing in construction, material or design but capable of providing traction equal to or exceeding that of chains under similar conditions (Idaho Code 49-948(6) and (7)). Idaho publishes no approved product list, so a device like AutoSock stands on that equivalence test rather than on a state approval.
• Check the live order: Idaho 511 (511.idaho.gov) and the ITD trucking page (trucking.idaho.gov) for the active pass order; watch the advance chain-up signs before Lookout, Fourth of July, and Lolo passes.
• Fine: Idaho Code 49-948 sets no chain-specific fine. Violating the posted chain-up order is a standard Idaho traffic offense, with the amount set on Idaho's penalty schedule by the court. Confirm the current figure with ITD or the court before you rely on a number.

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