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, plus one axle at or near the rear of each towed vehicle. Chains go on in addition to pneumatic tires. The order calls for tire chains, so snow tires do not substitute, and the statute does not recognize alternative traction devices like AutoSock for these passes.
• 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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