---
title: Montana Oversize & Overweight Permits (OS/OW) | MDT Superload | Alpine Truck Service
description: Expedited Montana MDT oversize permits, CANAMEX I-15 corridor routing, Bozeman Pass chain laws, and MHP escorts across I-90 and I-94. Call (918) 607-6547.
image: https://www.alpinetruckservice.com/alpine-third-party-charges.webp
---

# Montana Oversize, Overweight & Superload Permitting Services

Comprehensive commercial trucking permits and heavy haul compliance across Montana.

## Agency & Permitting Authority
- **Agency**: Montana Department of Transportation (MDT)
- **Portal**: MDT Motor Carrier Services e-Permitting Portal
- **Regulatory Advisory**: State DOT regulations and permit processing queues are determined by individual state transportation authorities and vary by agency workload. Carriers should verify active route advisories and state requirements prior to movement.

## Legal vs. Routine Permitted Dimensions
- **Legal Width**: 8' 6" | **Max Routine**: 18' 0"
- **Legal Height**: 14' 0" | **Max Routine**: 17' 0"
- **Legal Length**: 53' Semi-Trailer / 75' Overall | **Max Routine**: 150' 0"
- **Legal Gross Weight**: 80,000 lbs (up to 131,060 lbs on state routes with standard Bridge Formula B axle counts) | **Max Routine**: 160,000 lbs
- **Axle Limits**: Single: 20,000 lbs, Tandem: 34,000 lbs, Tridem: 42,000 lbs

## Permitting Scope & Services in Montana
- **Routine Oversize (OS) Cab-Cards**: Single-trip authorizations for dimensions exceeding 8' 6" width or 14' 0" height.
- **Overweight (OW) Axle Permits**: Overload cab-cards for heavy machinery and configurations exceeding 80,000 lbs GVW.
- **Multi-Axle Superload Permits**: Specialized filings exceeding Over 160,000, including State DOT and certified partner bridge reviews, route surveys, and police escorts.
- **Annual & Blanket Fleet Permits**: Continuous-operation annual highway authorizations for construction fleets.
- **Temporary Trip & Fuel Permits**: 72-hour IRP vehicle registration and IFTA fuel tax credentials.
- **County, City & Toll Road Clearances**: Municipal authorizations and turnpike clearances.

## Superload Permitting & State Review Protocol
- **Weight Trigger**: Over 160,000 lbs GVW or exceeding Montana Bridge Formula limits
- **Width Trigger**: Over 18' 0" wide
- **Height Trigger**: Over 17' 0" high
- **Length Trigger**: Over 150' 0" overall length
- **State & Partner Bridge Review**: Montana Department of Transportation (MDT) electronic systems and certified structural engineering partners evaluate axle load distribution across bridge structures upon submission.
- **Route Surveys & Clearances**: Required for extreme heights/widths to verify overhead physical clearances.
- **Utility & Escorts**: Coordinated wire lifts with power utilities and State Police / Highway Patrol escorts.

## Pilot Cars & Escort Vehicle Requirements
- **Front Escort**: Required over 12' 6" wide on two-lane highways
- **Rear Escort**: Required over 14' 0" wide on multi-lane highways or length exceeding 110' 0"
- **Height Pole**: Required over 15' 6" high (front escort with calibrated height pole)
- **Police Escort**: Montana Highway Patrol (MHP) escort required over 18' 0" wide, 18' 0" high, or over 160,000 lbs

## Metro Curfews & Travel Restrictions
- **Curfew Zones**:
  - Billings Metro (I-90, US-87): 7:00–8:30 AM & 4:30–6:00 PM M-F (loads >12' wide)
  - Missoula (I-90, US-93) and Bozeman (I-90) during peak commuter hours
- **Travel Rules**: Daylight only (1/2 hour before sunrise to 1/2 hour after sunset), 7 days a week for routine loads up to 15' wide. Overweight-only continuous travel allowed with lighting.

## Key Freight Corridors
- I-90 (Northern Transcontinental Spine)
- I-94 (Billings to North Dakota Bakken)
- I-15 (Salt Lake City to Alberta CANAMEX Corridor)
- US-2 (Hi-Line)
- US-12
- US-87

## Frequently Asked Questions
### What is Montana's legal height limit?
Montana permits a legal height of 14'0" on state and federal highways without requiring an oversize permit.

### What are Montana pilot car requirements for wide loads?
Montana mandates 1 escort for loads over 12'6" wide on 2-lane roads and over 14' wide on multi-lane highways. Loads over 110' long require a rear escort.

### Can oversize loads travel on weekends in Montana?
Yes, routine oversize loads up to 15' wide and 17' high are permitted to travel 7 days a week during daylight hours.

### How fast can Alpine obtain a Montana MDT permit?
Routine single-trip permits are processed in 2–4 business hours through MDT's electronic system. Alpine audits routes upon intake to accelerate issuance.

## Contact & Direct Dispatch
- **Direct Phone**: (918) 607-6547 (CALL: [918-607-6547](tel:9186076547))
- **Email**: [permits@alpinetruck.com](mailto:permits@alpinetruck.com)
- **Online Intake**: [alpinetruckservice.com/permits/montana](https://www.alpinetruckservice.com/permits/montana)