Montana Oversize Load Permit Requirements
Legal truck dimensions, oversize load travel hours, pilot car and escort requirements, and how to order an oversize/overweight permit from Montana Department of Transportation, Motor Carrier Services (MCS).
MT, reviewed October 2026
Check your load for Montana
Oversize permit required in Montana
- Width 10 ft 0 in exceeds the 8 ft 6 in legal limit.
No width-based pilot car at 10 ft 0 in wide.
Montana Truck Legal Width, Height & Length
A truck and load at or under these dimensions can travel Montana highways without an oversize permit. Exceed any one of them and you need a permit before you move.
| Legal width | 8 ft 6 in |
|---|---|
| Legal height | 14 ft 0 in |
| Legal length | Tractor with one trailer up to 53 ft needs no length permit regardless of overall length; single power unit 55 ft; single-trip oversize permit needed for loads over 75 ft long. |
| Gross weight | 80,000 lbs |
Montana Oversize Load Travel Hours
- Daily movement window
- Interstate: 24 hours/7 days up to 18 ft wide. Non-interstate: 24 hours up to 10 ft wide, 150 ft long and 15'6" high; anything larger is daylight hours only.
- Weekend movement
- Interstate allowed up to 18 ft wide. Non-interstate loads over 18 ft wide, 150 ft long or 17 ft high may not travel on weekends.
- Holiday restrictions
- Holiday weekend travel on interstates is allowed up to 18 ft wide (24 hrs); loads over 18 ft wide may not travel. Non-interstate: up to 10 ft wide/150 ft long/15'6" high allowed 24 hrs; over 10 to 12'6" wide daylight only; over 12'6" wide, 150 ft long or 15'6" high prohibited. Holiday weekend: holiday on Fri/Sat bars Fri-Sun; on Sun/Mon bars Sat-Mon; Tue-Thu that day only; Thanksgiving bars Thu-Sun (ARM 18.8.101). See this year's holiday dates for all states.
Montana Pilot Car Requirements
Interstate: one rear pilot over 16'6" wide and two rear pilots over 18'; non-interstate: one front pilot over 12'6" wide, front and rear over 16'6", more at 18'+; height pole front pilot over 17' high; rear pilot over 150' long (non-interstate).
| First pilot car (width) | 16 ft 6 in wide and over |
|---|---|
| Two pilot cars (width) | 18 ft 0 in wide and over |
| Height-pole escort | 17 ft 0 in tall and over |
| Length escort | 150 ft 0 in long and over |
Montana pilot car requirements by load width and height. Crossing a border? Compare with Idaho, Wyoming.
How to order a Montana oversize permit
Montana Department of Transportation, Motor Carrier Services (MCS)
Overweight as well? Check axle limits with the bridge formula calculator.
Crossing Montana without Montana apportioned plates? Estimate the temporary trip permit cost with the trip permit cost estimator.
Montana Oversize Load FAQs
- What are the oversize load travel hours in Montana?
- Interstate: 24 hours/7 days up to 18 ft wide. Non-interstate: 24 hours up to 10 ft wide, 150 ft long and 15'6" high; anything larger is daylight hours only. Weekends: Interstate allowed up to 18 ft wide. Non-interstate loads over 18 ft wide, 150 ft long or 17 ft high may not travel on weekends.
- When is a pilot car required in Montana?
- Interstate: one rear pilot over 16'6" wide and two rear pilots over 18'; non-interstate: one front pilot over 12'6" wide, front and rear over 16'6", more at 18'+; height pole front pilot over 17' high; rear pilot over 150' long (non-interstate). Height: 17 ft 0 in and taller (height-pole escort).
- What is the legal truck width in Montana?
- The standard legal width in Montana is 8 ft 6 in (102 inches), the federal minimum width allowed on the National Network of highways. A load wider than that needs an oversize permit.
- How tall can a truck be in Montana without a permit?
- The legal height limit in Montana is 14 ft 0 in, measured from the road surface to the highest point of the vehicle or load. Taller loads need an oversize permit and a surveyed route for bridge and wire clearances.
- Can oversize loads move on holidays in Montana?
- Holiday weekend travel on interstates is allowed up to 18 ft wide (24 hrs); loads over 18 ft wide may not travel. Non-interstate: up to 10 ft wide/150 ft long/15'6" high allowed 24 hrs; over 10 to 12'6" wide daylight only; over 12'6" wide, 150 ft long or 15'6" high prohibited. Holiday weekend: holiday on Fri/Sat bars Fri-Sun; on Sun/Mon bars Sat-Mon; Tue-Thu that day only; Thanksgiving bars Thu-Sun (ARM 18.8.101).
- How do I get an oversize or overweight permit in Montana?
- Apply through Montana Department of Transportation, Motor Carrier Services (MCS) (406-444-7262) or its online permit portal. Have your USDOT number, vehicle and load dimensions, axle weights and route ready. Permit expediting agents can file on your behalf if you need the permit the same day.
Regulations change. This page summarises published Montana rules as reviewed October 2026 and is not legal advice; the conditions printed on your permit control. Note: Escort thresholds differ by road: interstate-only rear pilots (16'6"+/18'+); non-interstate 12'6"+ front. escortOneWidthFt uses the interstate figure. Legal 80,000 lb gross is the standard interstate limit and was not explicitly confirmed in the fetched text. Holiday end time not stated in the restrictions list. County/city permits may also be needed.