MT state page · Last reviewed 2026-05-25
Montana Truck Weight Limits and Permit Sources Montana truck weight reference with official permit links, FHWA weight source tracking, and conservative seasonal and fine status labels.
This page is a reference aid, not legal advice. Weight rules, permits, routes,
and penalties can change without notice; use the linked official source as the
final authority.
At-a-glance summary Field Value Source Status Confidence Gross Federal Interstate gross limit is 80,000 lb; Montana-specific limits are in the FHWA state law compilation linked here. inferred from official source medium Single axle Federal Interstate single-axle limit is 20,000 lb; Montana-specific limits are in the FHWA state law compilation linked here. inferred from official source medium Tandem axle Federal Interstate tandem limit is 34,000 lb; Montana-specific limits are in the FHWA state law compilation linked here. inferred from official source medium Bridge formula Federal bridge formula checks apply on Interstate routes; verify state exceptions and permit conditions before movement. inferred from official source medium Permit agency Montana Department of Transportation confirmed high Seasonal / frost No official statewide seasonal or frost weight restriction was confirmed during this review. No confirmed official source Needs official confirmation
not found in official review low Fine source Montana Code Annotated section 61-10-145 is the official source reviewed for excess weight penalties. confirmed medium
Field-level reference data Regular weight limits Gross vehicle weight limit Federal Interstate gross limit is 80,000 lb; Montana-specific limits are in the FHWA state law compilation linked here. inferred from official source medium Single axle limit Federal Interstate single-axle limit is 20,000 lb; Montana-specific limits are in the FHWA state law compilation linked here. inferred from official source medium Tandem axle limit Federal Interstate tandem limit is 34,000 lb; Montana-specific limits are in the FHWA state law compilation linked here. inferred from official source medium Bridge formula applies Federal bridge formula checks apply on Interstate routes; verify state exceptions and permit conditions before movement. inferred from official source medium Interstate notes Use FHWA Interstate limits together with the state source and any permit conditions. inferred from official source medium Non-Interstate notes Use the reviewed state source and local postings for non-Interstate operation. inferred from official source medium
Axle and loading notes Steer axle notes Steer axle review should include axle law, tire/equipment ratings, registration, and route postings. inferred from official source medium Drive axle notes Drive axle groups should be checked against tandem/group limits and permit terms. inferred from official source medium Trailer tandem notes Trailer tandem position changes distribution and may affect spacing-sensitive checks; re-weigh after adjustment. inferred from official source medium Fifth wheel notes Fifth-wheel movement redistributes weight but does not create permit authority. inferred from official source medium Bridge law notes Check FHWA bridge formula and the state source when axle spacing is close to a limit. inferred from official source medium
Oversize / overweight permits Permit agency Montana Department of Transportation confirmed high Permit office name MDT Motor Carrier Services Permits confirmed high Official permit URL Montana MDT motor carrier permit source. confirmed high Online permit portal Use MDT Motor Carrier Services Permits official source for current online filing or portal links. inferred from official source medium Permit contact Use contact information published by MDT Motor Carrier Services Permits. inferred from official source medium Permit notes Permit terms, route conditions, dates, and vehicle configuration should be checked on the official permit source before travel. inferred from official source medium
Seasonal and special restrictions Frost / seasonal restriction No official statewide seasonal or frost weight restriction was confirmed during this review. No confirmed official source Needs official confirmation
not found in official review low Seasonal weight notes Local route, bridge, or permit restrictions may still apply; no statewide seasonal weight restriction was confirmed in this review. No confirmed official source Needs official confirmation
not found in official review low Official seasonal URL No confirmed official source Needs official confirmation
not found in official review low
Fines and enforcement Overweight fine structure Montana Code Annotated section 61-10-145 is the official source reviewed for excess weight penalties. confirmed medium Overweight ticket notes Use MCA section 61-10-145 with the actual citation and permit terms before estimating a penalty. inferred from official source medium Enforcement agency Montana Department of Transportation Motor Carrier Services Enforcement confirmed medium Fine official URL Official fine or penalty source linked in Sources. confirmed medium CSA / safety notes CSA impact depends on inspection and reporting; use FMCSA SMS materials and the actual inspection record. inferred from official source medium
Scale notes Public scale notes A public scale ticket is a self-check record, not state permit authority. inferred from official source medium Weigh station / enforcement notes Montana MDT Motor Carrier Services enforcement is the reviewed official enforcement source. inferred from official source medium CAT Scale disclaimer CAT Scale tickets are private self-check records and do not replace official permits or enforcement decisions. inferred from official source medium Scale ticket notes Use steer, drive, trailer, and gross readings to compare against official limits before travel. inferred from official source medium
Montana has some of the longest rural freight distances in the contiguous United States — agricultural grain, livestock, timber, and oil-field equipment loads move on US highways and county roads with minimal Interstate coverage outside I-90 and I-15. MDT (Montana Department of Transportation) administers OS/OW permits through Motor Carrier Services; agricultural commodity exemptions are part of Montana statute and should be confirmed for specific load types. Remote route conditions and limited fuel and service availability are operational factors that intersect with permit route requirements on longer hauls.
How to verify this yourself
Open MDT Motor Carrier Services permit materials for over-legal movement and verify applicable agricultural exemptions through Montana statute. Check non-Interstate route postings before departure.
FAQ Where should I verify Montana permit requirements? Use the official MDT Motor Carrier Services Permits source linked on this page before moving over legal size or weight.
Are Montana seasonal restrictions confirmed here? No. This review did not confirm a statewide seasonal or frost source, so route and permit restrictions still need checking.
Are Montana overweight fines confirmed here? No. A specific official fine schedule was not confirmed in this review.