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Montana · Oversize & Overweight

Montana Oversize & Overweight Permits filed with MDT for you, 24/7

In Montana, oversize and overweight permits come from MDT Motor Carrier Services through eTRIPS. A load over 8 ft 6 in wide, 14 ft high or 75 ft long on a truck-and-trailer combination needs one. Going over 80,000 lbs gross takes no special permit by itself, but the truck must be licensed for the weight. On interstates, permitted loads up to 18 ft wide run 24/7, holidays included. Send us the load and route: our permit desk quotes the price and files it for you.

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What will an oversize permit in Montana cost?

Enter your pickup and delivery locations, choose your permit type, and compare estimated permit costs across route options.

  1. Oversize and overweight permits across the lower 48 and DC
  2. State-by-state fee breakdown for each route option
  3. Order your permit or talk to a specialist
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Montana rules

Montana legal limits and permit rules

The size and weight Montana allows without a permit, how many pilot cars a load needs and when a permitted load may run.

Legal limits without a permit

Width
8 ft 6 in
Height
14 ft
Truck-and-trailer combination
75 ft
Single axle
20,000 lbs
Tandem axle
34,000 lbs
Gross, reducible loads
Up to 131,060 lbs

Pilot cars

Non-interstate, over 12 ft 6 in wide
1 front
Non-interstate, over 16 ft 6 in wide
Front and rear
Non-interstate, over 18 ft wide
2 front, 1 rear
Non-interstate, over 24 ft wide
2 front, 2 rear
Interstate, over 16 ft 6 in to 18 ft wide
1 rear
Interstate, over 18 ft wide
At least 2 rear, side by side
Over 17 ft high
Front pilot car with a height pole
Over 24 ft high
Front pole car and rear pilot car
Non-interstate, over 150 / 200 ft long
1 rear / front and rear

When you can move

Interstates
24/7 up to 18 ft wide, holidays included
Non-interstate, around the clock
Up to 10 ft wide, 150 ft long and 15 ft 6 in high
Non-interstate, larger loads
Daylight only
Non-interstate weekends
No travel over 18 ft wide, 150 ft long or 17 ft high
Holidays
New Year's, Memorial Day, July 4, Labor Day, Thanksgiving (Thursday to Sunday), Christmas
Holidays, non-interstate
Up to 10 ft wide 24/7; 10 to 12 ft 6 in daylight; over 12 ft 6 in wide, 150 ft long or 15 ft 6 in high parked
Road conditions
No travel on a route under severe driving conditions

Source: MDT Motor Carrier Services — eTRIPS permit restrictions, Permitting FAQ, 2026 Trucker's Handbook, holiday list and superload instructions; ARM 18.8; MCA 61-10. Your permit's own conditions always apply.

Which permit you need

Montana permits for oversize and overweight loads

  1. One trip on set dates

    Single-trip permit

    One trip within the dates printed on the permit, ordered through eTRIPS.

  2. Repeat moves through the year

    Term permit

    Annual term permits expire December 31; overweight term permits are also sold by the quarter or the half-year.

  3. Over 18 ft wide, 17 ft high or 150 ft long

    Superload permit

    Class 1, up to 34 ft wide, 24 ft high or 200 ft long, is decided within two working days; Class 2, anything larger, within five. An approval stays good for 60 days.

  4. 10% over legal weight

    Winter weight permit

    Adds 10% to legal weight, up to 132,000 lbs gross. Not valid on interstates.

Routes and road rules

Where Montana routes add their own rules

Interstates carry the big loads around the clock; a few two-lane segments and the border corridors have limits of their own.

  1. Montana interstates

    Permitted loads up to 18 ft wide run 24/7, holidays included. From over 16 ft 6 in to 18 ft wide, one pilot car follows; over 18 ft, at least two rear pilot cars run side by side.

    Off the interstate:Loads over 10 ft wide, 150 ft long or 15 ft 6 in high run in daylight only.

  2. MT-35, Polson to Bigfork

    The segment between Polson and Bigfork is restricted for loads over 9 ft wide.

    Route:We plan another way for wider loads.

  3. US-87, Belt to Raynesford

    Permanently limited to 12 ft 6 in wide, with set detours for anything wider.

    Over 12 ft 6 in:The load follows the set detour.

  4. Canadian-weight corridors

    I-15 from Shelby to Sweet Grass, US-93 from the BC border to 10 miles south near Eureka, and MT-16 from the Saskatchewan border to 20 miles south near Plentywood allow B-trains up to 137,500 lbs.

    B-trains:Up to 137,500 lbs on these segments only.

Montana loads

Montana permits for the loads Montana hauls

Beside the general permits, MDT sets terms written for timber, hay and harvest equipment.

  1. Timber

    Raw logs

    Up to 9 ft wide, 75 ft long and 15 ft 6 in high; five-axle log combinations up to 80,000 lbs.

  2. Logging

    Logging equipment

    Up to 15 ft wide, 15 ft 6 in high and 95 ft long.

  3. Hay

    Baled hay

    Up to 12 ft wide and 15 ft 6 in high.

  4. Harvest and farm equipment

    Custom combines and implement dealers

    Custom combines get a 20% weight tolerance within a 100-air-mile radius. Montana implement dealers are not held to the weekend and holiday travel rules.

How it works

Your Montana permit in three steps

  1. Send the load and route

    Truck, trailer, dimensions, weight, origin and destination. Your fleet details are saved for next time.

  2. We check and file

    Our permit desk checks the Montana rules for your load and files with MDT Motor Carrier Services.

  3. Get your permit

    You get the permit PDF, a written route and an interactive route map to share with the driver.

From our permit desk

What we check before filing in Montana

  1. Holiday blocks run longer than the holiday

    Thanksgiving blocks Thursday through Sunday. A Friday or Saturday holiday blocks Friday through Sunday, a Sunday or Monday holiday Saturday through Monday. We check your dates against the whole block.

  2. The superload class sets the clock

    Over 18 ft wide, 17 ft high or 150 ft long, the load files as a superload: up to two working days for Class 1, five for Class 2. We file early, and the approval holds for 60 days.

  3. Licensed weight comes first

    Montana needs no special permit just to go over 80,000 lbs, but the truck must be licensed for the weight. We check the registered weight against the load before we file.

FAQ

Montana oversize permit questions

Which Montana loads need an MDT permit?

Loads over 8 ft 6 in wide, 14 ft high or 75 ft for a truck-and-trailer combination, and axles over 20,000 lbs single or 34,000 lbs tandem. Gross weight over 80,000 lbs needs no special permit by itself as long as the truck is licensed for it; reducible loads top out at 131,060 lbs.

How much does a Montana oversize permit cost?

It depends on the permit type, size, weight and route. Put your route into our permit cost calculator for an estimate, or send us the load and our permit desk quotes the exact price before filing.

Do Montana interstates close to wide loads on holidays?

No. On interstates, loads up to 18 ft wide may run 24/7, holidays included. Off the interstate, a holiday parks loads over 12 ft 6 in wide, 150 ft long or 15 ft 6 in high, and loads from 10 to 12 ft 6 in wide run in daylight only.

How many pilot cars does Montana require on two-lane highways?

Off the interstate: one front pilot car over 12 ft 6 in wide, front and rear over 16 ft 6 in, two front and one rear over 18 ft, two and two over 24 ft. Length adds a rear car over 150 ft and front and rear over 200 ft.

What turns a Montana load into a superload?

More than 18 ft of width, 17 ft of height or 150 ft of length. Class 1 covers up to 34 ft wide, 24 ft high or 200 ft long and is decided within two working days; Class 2 goes beyond that and takes up to five. An approval stays good for 60 days.

Where can B-trains run Canadian weights in Montana?

On three border corridors: I-15 from Shelby to Sweet Grass, US-93 from the BC border to 10 miles south near Eureka, and MT-16 from the Saskatchewan border to 20 miles south near Plentywood. B-trains may run up to 137,500 lbs there.

How does Route One GO get my Montana permit?

Send us the truck, trailer, load dimensions, axle weights and route. Our permit desk checks the Montana rules, files with MDT Motor Carrier Services in eTRIPS, and sends you the permit with a route map. Requests are taken 24/7.

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