Montana Trucking Regulations

Montana follows the federal 80,000 lbs GVW limit on interstate highways but allows heavier configurations on state highways. The Montana Department of Transportation (MDT) issues oversize/overweight permits through the Motor Carrier Services Bureau. Single-trip permits start at $25. Montana allows up to 131,060 lbs on certain state routes with proper multi-axle configurations — one of the highest state allowances nationally. The state's Gross Vehicle Weight Table specifies allowable weights by number of axles and wheelbase. MDT operates ports of entry on I-90, I-15, I-94, and US-93. Overweight fines are calculated by the excess amount, starting at $50 for the first 1,000 lbs over. Spring breakup weight restrictions (March-May) affect many secondary and unpaved roads.

Montana's mountainous terrain in the western half of the state creates significant trucking challenges. Lookout Pass (I-90), Homestake Pass (I-90), Pipestone Pass (I-15), and MacDonald Pass (US-12) all have steep grades requiring brake checks and lower gears. Montana does not have a mandatory chain law but strongly recommends traction devices November through April on mountain passes. MDT provides variable message signs and the 511 travel information system for current conditions. Commercial vehicles must maintain safe speeds on grades — runaway truck ramps are located on several mountain descents. The Beartooth Highway (US-212) and Going-to-the-Sun Road in Glacier National Park have seasonal truck restrictions. Wind restrictions on I-90 near Livingston can close the highway to high-profile vehicles during severe wind events.

Montana requires intrastate carriers to register with MDT Motor Carrier Services. The state follows federal HOS and ELD regulations. Montana does not require periodic safety inspections — enforcement relies on roadside inspections at ports of entry and during roving patrols by the Montana Highway Patrol Motor Carrier Division. The state enforces IFTA and IRP requirements. Montana has specific regulations for livestock transport, reflecting the state's major ranching industry. The state allows longer combination vehicles (LCVs) including Rocky Mountain doubles on designated routes. Montana has no general state speed limit for commercial vehicles beyond the posted limits (80 mph on most interstates) — trucks follow the same speed limits as cars.