Montana Oversize Load Regulations & Permit Requirements
Important: We are not a permit service and we do not arrange permits for carriers. All information provided below is for informational purposes only. Always read permits and provisions carefully as we cannot guarantee the accuracy of information provided below.
Montana DOT Ph#: 406-444-7262
For companies specializing in heavy equipment transport or machinery hauling services, understanding Montana’s oversize load safety regulations is essential for smooth operations. Here’s what you need to know:
Permit Information
- Permit Validity: Oversize permits are valid for 3-5 days.
- Single-trip Permits: Required for most oversized movements.
- Flexibility: Montana offers unique flexibility for heavy haul transport of divisible loads exceeding 80,000 lbs without permits when axle weights are legal.
Operating Hours for Oversized Load Transportation
- Continuous Travel: Allowed for loads ≤10′ wide, ≤15’6″ high, ≤110′ long.
- Daylight-Only Movement: Allowed for loads ≤18′ wide, ≤18′ high, ≤120′ long (½ hour before sunrise to ½ hour after sunset).
- Special DW21 Conditions: Apply on two-lane highways:
- Requires two pilot cars for certain weights.
- May impose 5 MPH speed restrictions.
Restricted Travel (Red Route Highways)
- Weekend Restrictions: For larger loads:
- 10′ wide/14’6″ high/110′ long: No travel after 3 PM Friday until sunrise Monday.
- 18′ wide/18′ high/120′ long: Complete weekend shutdown (4 PM Friday to Monday sunrise).
- Holiday Travel: Typically limited to loads ≤10′ wide/14’6″ high/110′ long.
Legal Dimensions for Heavy Haul Trucks
Length:
- 53′ semi-trailer standard
- 75′ max: Including overhang (permits required beyond this).
Width:
- 8’6″: Standard width.
Height:
- 14′: Standard height.
Weight Limits:
- Gross: 80,000 lbs.
- Single axle: 20,000 lbs.
- Tandem: 34,000 lbs.
- Tridem: 42,000 lbs.
Routine Permit Limits
- Length: Up to 150′.
- Width: Up to 18′.
- Height: Up to 17′.
- Weight Limits:
- Single axle: 24,000 lbs
- Tandem: 48,000 lbs*
- Tridem: 62,700 lbs*
- (*Varies by axle spacing)
Escort Requirements for Oversize Load Safety
Interstate Highways:
- Length >120′: 1 escort.
- Width >16′6″: 1 escort.
- Height >17′: Route-specific requirements.
Two-Lane Highways:
- Length >110′: 1 escort.
- Width >12′6″: 1 escort.
- Width >14′: 2 escorts.
- Weight >54,300-55,000 lbs on tridem: 2 escorts (DW21 conditions).
Safety & Compliance for Transporting Large Equipment
Signage:
- “Oversize Load” Signs: Required for loads >10′ wide.
Amber Warning Lights:
- Minimum 5″: Required at both ends.
Long Load Signs:
- For Combinations: >105′ (non-Interstate) or >120′ (Interstate).
Flags:
- Flags: Required marking all extreme projections.
Seasonal Considerations
- Spring Thaw Restrictions: From February to May, which may affect some routes.
- Interstate Routes: Typically remain unrestricted during thaw periods.
- Route Planning: For overweight vehicles should account for seasonal changes.