Montana Truck Speed Limit
Split state. Trucks are capped at 70 mph on rural interstates where cars run 80 (MCA 61-8-303), a 10 mph gap. On two-lane highways trucks do 70 by day and drop to 65 at night. Montana scrapped its old 'reasonable and prudent' non-limit years ago, so the number is enforced now.
How fast a truck can run in Montana
Split state. Trucks are capped at 70 mph on rural interstates where cars run 80 (MCA 61-8-303), a 10 mph gap. On two-lane highways trucks do 70 by day and drop to 65 at night. Montana scrapped its old 'reasonable and prudent' non-limit years ago, so the number is enforced now.
Truck-specific rules and quirks
- Night limit: 65 mph for trucks on two-lane highways at night
- Montana raised the truck interstate limit from 65 to 70 in 2015; cars run 80. The old 'reasonable and prudent' daytime non-limit is long gone.
What a speeding ticket costs
Speeding is a graduated fine. Work-zone penalties double.
Montana Truck Speed Limit FAQ
What is the truck speed limit in Montana?
Do trucks have a lower speed limit than cars in Montana?
What is the speeding penalty for a truck 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 Traffic laws change and this can be out of date, so always confirm the current statute and obey posted signs before you rely on it.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://www.iihs.org/topics/speed/speed-limit-laws. See our Terms & Disclaimer.
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