Montana Studded Tire Law
Metal studs are legal October 1 through May 31 (MCA 61-9-406), one of the longest windows in the country. School buses get August 15 to June 15, and retractable studs run any month. Montana sets no GVW cap, so a loaded truck can run studs in season, capped at 1/16-inch projection. MDT's posted tire or traction signs may not bar in-season studs. When MDT decides chains are required and nothing else will do, you chain the driver wheels of one axle, studded tires included (MCA 61-9-406(7)).
Running studs in Montana
Metal studs are legal October 1 through May 31 (MCA 61-9-406), one of the longest windows in the country. School buses get August 15 to June 15, and retractable studs run any month. Montana sets no GVW cap, so a loaded truck can run studs in season, capped at 1/16-inch projection. MDT's posted tire or traction signs may not bar in-season studs. When MDT decides chains are required and nothing else will do, you chain the driver wheels of one axle, studded tires included (MCA 61-9-406(7)).
The window and winter-tire rules
- Season: October 1 to May 31 (MCA 61-9-406). School buses: August 15 to June 15. Pneumatic tires with retractable studs may be used any month.
- No statewide M+S or 3PMSF mandate. MDT can post tire, chain, or traction device requirements when highway conditions are dangerous (MCA 61-9-406(6)). From October 1 to May 31 those signs may not bar studded tires within the 1/16-inch projection limit. When MDT decides chains are required and no other traction device will do, chains go on the driver wheels of one axle even if those tires are studded (MCA 61-9-406(7)). Truck weight cap: none, studs legal for trucks in season. See the Montana chain-law page.
Montana Studded Tire FAQ
Are studded tires legal in Montana?
When can you use studded tires in Montana?
What is the fine for illegal studded tires in Montana?
Reference information for planning, not legal advice. Traffic laws change and this can be out of date, so always confirm the current statute and obey posted signs before you rely on it. Last reviewed July 2026. Source: https://mca.legmt.gov/bills/mca/title_0610/chapter_0090/part_0040/section_0060/0610-0090-0040-0060.html. See our Terms & Disclaimer.
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