Do Idaho and Montana require pilot cars at the same width?

Idaho requires a pilot car from 12 ft 1 in wide; Montana waits until 16 ft 6 in. A load between those widths needs an escort in Idaho only.

Is the legal truck height the same in Idaho and Montana?

Both states use the same legal height, 14 ft 0 in.

Do I need a separate permit for each state between Idaho and Montana?

Yes. Oversize and overweight permits are issued by each state, so a move through both needs a permit from Idaho Transportation Department (Commercial Vehicle Services / Permits4Idaho) and one from Montana Department of Transportation, Motor Carrier Services (MCS), each with its own route, hours and escort conditions.

Which travel hours apply in Idaho and Montana?

Idaho: Loads not over 12 ft wide, 120 ft long and 15 ft high may travel 24 hours, 7 days (black-coded routes and interstate). Larger loads are daylight-only per the ITD pilot/escort map. Loads over 13 ft wide barred 6-9 am and 4-6:30 pm Mon-Fri at listed commuter areas (Boise valley I-84, Coeur d'Alene, Idaho Falls, Twin Falls, etc.). 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. The conditions printed on the permit control.

Idaho vs Montana Oversize Load Rules

What changes for an oversize load between Idaho and Montana: legal height, pilot car triggers, height poles and travel hours.

I-90, reviewed October 2026

What changes at the Idaho and Montana border

Legal height: Both states use the same legal height, 14 ft 0 in.
First pilot car: Idaho requires a pilot car from 12 ft 1 in wide; Montana waits until 16 ft 6 in. A load between those widths needs an escort in Idaho only.
Second pilot car: Idaho adds a second escort at 14 ft 1 in wide; Montana at 18 ft 0 in.
Height pole: Idaho requires a height-pole escort from 16 ft 0 in; Montana from 17 ft 0 in.

Check one load against both states

Load width (ft)

Load height (ft)

Idaho

Oversize permit required
No width escort

Montana

Oversize permit required
No width escort

11 ft 0 in wide, 14 ft 0 in tall. Length is not checked here.

Side by side

Idaho and Montana oversize load rules compared
Rule	Idaho	Montana
Legal width	8 ft 6 in	8 ft 6 in
Legal height	14 ft 0 in	14 ft 0 in
Legal length	Single motor vehicle 45 ft; semitrailer 48 ft (53 ft on national network and access routes); truck-tractor with semitrailer and trailer (doubles) 75 ft overall, 61 ft trailers combination (68 ft on national network); 115 ft on designated LCV routes by permit (Idaho Code 49-1010).	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	80,000 lbs
First pilot car at	12 ft 1 in	16 ft 6 in
Second pilot car at	14 ft 1 in	18 ft 0 in
Height pole at	16 ft 0 in	17 ft 0 in
Length escort at	120 ft 0 in	150 ft 0 in
Travel hours	Loads not over 12 ft wide, 120 ft long and 15 ft high may travel 24 hours, 7 days (black-coded routes and interstate). Larger loads are daylight-only per the ITD pilot/escort map. Loads over 13 ft wide barred 6-9 am and 4-6:30 pm Mon-Fri at listed commuter areas (Boise valley I-84, Coeur d'Alene, Idaho Falls, Twin Falls, etc.).	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	Red-coded routes: daylight only until 2 pm Friday, no Saturday or Sunday travel, resumes Monday at sunrise. Black-coded and interstate: loads within 12 ft wide / 120 ft long / 15 ft high may travel weekends; larger loads follow the pilot map restrictions.	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.
Trip permit	$60.00	Fee not confirmed
Permit office	Idaho Transportation Department (Commercial Vehicle Services / Permits4Idaho)	406-444-7262 (Montana Department of Transportation, Motor Carrier Services (MCS))

Go deeper

Pilot car detail: Idaho, Montana
Full guides: Idaho, Montana
Running through both without local plates? Estimate the trip permit cost
Moving over a holiday? Check holiday restrictions

Idaho and Montana FAQs

Do Idaho and Montana require pilot cars at the same width?: Idaho requires a pilot car from 12 ft 1 in wide; Montana waits until 16 ft 6 in. A load between those widths needs an escort in Idaho only.
Is the legal truck height the same in Idaho and Montana?: Both states use the same legal height, 14 ft 0 in.
Do I need a separate permit for each state between Idaho and Montana?: Yes. Oversize and overweight permits are issued by each state, so a move through both needs a permit from Idaho Transportation Department (Commercial Vehicle Services / Permits4Idaho) and one from Montana Department of Transportation, Motor Carrier Services (MCS), each with its own route, hours and escort conditions.
Which travel hours apply in Idaho and Montana?: Idaho: Loads not over 12 ft wide, 120 ft long and 15 ft high may travel 24 hours, 7 days (black-coded routes and interstate). Larger loads are daylight-only per the ITD pilot/escort map. Loads over 13 ft wide barred 6-9 am and 4-6:30 pm Mon-Fri at listed commuter areas (Boise valley I-84, Coeur d'Alene, Idaho Falls, Twin Falls, etc.). 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. The conditions printed on the permit control.

Compiled from each state's published permit rules, reviewed October 2026. Not legal advice; the conditions printed on your permit control.