Are studded tires legal in Idaho?

Yes, within a season. Idaho allows studded tires from October 1 through April 30. Idaho Code 49-948 reads: "Motor vehicles, trailers and semitrailers with tires having built-in studs are prohibited on public highways between the dates of May 1 and September 30, annually, except as provided in paragraphs (a), (b) and (c) of this subsection:"

From October 1. For the 2026-27 season that is Thursday, October 1, 2026, and the window runs through Friday, April 30, 2027.

April 30 is the last day of the window, which for 2026-27 is Friday, April 30, 2027. The statute gives no DOT extension of the window itself; the Idaho Transportation Board may grant special exemptions from the prohibited dates.

The statute gives no DOT extension of the window itself; the Idaho Transportation Board may grant special exemptions from the prohibited dates. The statute reads: "(c) Special exemptions from the prohibited dates may be granted by the Idaho transportation board if it is found by the board that enhancements to public safety outweigh the increased pavement wear."

Fire department pumper, tanker and ladder trucks are exempt from the prohibited dates. The Idaho Transportation Board may grant special exemptions from the prohibited dates when public safety gains outweigh pavement wear. Retailers may not sell or install studs that protrude more than 0.06 inch or exceed set weights by stud size.

The statute's chain rule covers commercial vehicles on Interstate 90 over Lookout Pass and Fourth of July Pass and on State Highway 12 over Lolo Pass, when ITD finds conditions unsafe. It names no general chain law for passenger cars. The statute reads: "If the Idaho transportation department determines, at any time, that Lookout Pass or Fourth of July Pass on interstate 90 or Lolo Pass on state highway 12 is of an unsafe condition so as to require chains, as defined in section 49-104 , Idaho Code, in addition to pneumatic tires, the Idaho transportation department may establish requirements for the use of chains on all commercial vehicles"

Retractable studs may stay on year round if they retract to or below the wear bar when not in use and protrude only from October 1 to April 30. Tire chains are permitted.

Washington, November 1 through March 31; Oregon, November 1 through March 31; Nevada, October 1 through April 30; Utah, October 15 through March 31; Wyoming, no seasonal dates; Montana, October 1 through May 31. Each state's page quotes its own statute.