2021 Montana oversize and over-weight shipping laws and regulations.
Official 2021 Montana state over the road transport laws, regulations, and guidelines. Legal maximum dimensions and/or weight limits. Shipments in excess of the following weights/dimensions will require special permit approval from the state.
Maximum dimensions/weights allowed without a permit.
Any shipment exceeding any of the following dimensions or weights requires a special permit issued from the state.
Length: 75 feet maximum combined total overall.
Height: 14 feet.
Weight: 80,000 pounds. 20,000 pounds on any steer axle. Divisible loads may exceed 80,000 without an overweight permit as long as all axle group spacings and weights are legal. Truck drivers must have a special DMV endorsement for additional weight.
Maximum dimensions/weights of routinely permitted shipments.
If a proposed shipment is in excess of any of the following dimensions or weights it is considered a superload. Superloads require extensive review in order to be granted permits.
Length: 110 feet (33.528 meters).
Width: 18 feet (5.4864 meters).
Height: 17 feet (5.1816 meters) on most routes.
Weight: 100,000 pounds (45359.237 kilograms).
When pilot cars/escort vehicles are required.
If your shipment pertains to any of the following you will be required to have pilot cars or escorts.
Length: On two-lane roads over 105′ one pilot car or escort vehicle in the rear is required. Four lanes over 120’ only require one pilot car or escort vehicle in the rear.
Width: Two lanes over 12′ one pilot car or escort vehicle in front. Two lanes over 14′ one pilot car or escort vehicle in front and one pilot car or escort vehicle in the rear. Four lanes 14′ to 18′ one pilot car or escort in the rear.
Height: Not Specified; Up to the company because they are responsible for all structures.
Travel times and holiday restrictions.
Continuous travel is permitted for loads not exceeding 10′ wide, 15′-6″ high, or 110′ in length. Daylight hours are 1/2 hour before sunrise to 1/2 hour after sunset. Saturday and Sunday travel is allowed for loads not exceeding 18′ wide, 18′ high, or 120′ in length except on designated highways – refer to your actual permit instructions.
Restricted travel routes should be documented on your permit. Restricted routes do not permit travel after 3:00 pm Friday thru Saturday, and from 12:00 PM on Sunday until sunrise on Monday if the dimensions exceed 10′ wide, 14′-6″ high or 110′ in length. No travel is permitted after 4:00 pm Friday until Monday morning if the dimensions exceed 18′ wide, 18′ high, or 120′ in length.
Holiday travel is usually permitted for loads that do not exceed: 10′ wide, 14′-6″ high or 110′ in length.
Superload (class 1) Loads exceeding 18 feet wide up to 34 feet wide, 17 feet high up to 24 feet high, and/or 150 feet long up to 200 feet long, must obtain the appropriate department district administrator or designee approval of a completed super-load permit application. The department’s decision on a complete super-load application for these dimensions must be issued within two working days of a properly completed application submittal. At the discretion of the MCS administrator or designee, any restricted travel may be waived.
Superload (class 2) Loads exceeding 34 feet wide, 24 feet high, and/or 200 feet long must obtain the appropriate department district administrator or designee approval of the super-load permit application. The department’s decision on a super-load application for these dimensions must be issued within five working days of a properly completed application submittal. At the discretion of the MCS administrator or designee, any restricted travel may be waived.
Truck & trailer. Required lights, signs, banners, flags, etc.
(1) Vehicles exceeding 10 feet in width must:
(a) Display a sign with the words “OVERSIZE LOAD” or similar wording which must be mounted at any visible height on the front and rear of the load. Letters shall not be less than 8 inches in height. The letters shall be black in color on a yellow colored background with the exception of digital signs.
(b) On the power unit, flashing amber lights, a minimum of five inches in diameter, 50 candlepower, 60 to 90 flashes per minute, shall be mounted at each end of the oversize load sign and visible 360 degrees. A single revolving light or strobe light may be substituted for flashing lights. Lights shall be flashing at all times when moving an oversize vehicle or load.
(2) Pilot vehicles may be required under ARM 18.8.511A in lieu of “oversize load” signs and flashing lights.
(3) Towing vehicles must be equipped with two-way radio communications if pilot vehicles are required under ARM 18.8.511A.
(4) Oversize load signs must be removed from the vehicle upon completion of the highway movement which necessitated the signs.
Pilot cars/escort vehicles. Required lights, signs, banners, flags, etc.
(1) A pilot vehicle may be any passenger car or two-axle truck a minimum of 60 inches wide. The maximum manufacturer’s rating for the pilot vehicle shall not exceed a gross vehicle weight rating of 14,000 pounds. Service or mechanic trucks owned or contracted by the permittee and used as a pilot vehicle shall not exceed a gross vehicle weight rating of 26,001 pounds. A pilot vehicle may not exceed legal limits of size and weight. Trucks used as pilot vehicles shall be clearly distinguished from and identifiable as the escort vehicle. A pilot vehicle may pull a trailer or carry any item or equipment which:
(a) is within legal limits of size and weight;
(b) allows an unobstructed view of the flashing lights and signs used by the pilot vehicle;
(c) complies with all state traffic laws; and
(d) possesses current registration and valid insurance.
(2) Service or mechanic trucks used as pilot vehicles must not have a utility box that extends above the cab more than 12 inches or beyond the width of the cab more than 6 inches on either side.
(3) A sign with the words “oversize load” or similar wording shall be visible from the front of the vehicle and rear of the vehicle at all times when piloting an oversize load. Letters shall not be less than 8 inches in height. The letters shall be black in color on a yellow colored background with the exception of digital signs. When not being operated as a pilot vehicle, signs must be removed.
(4) Flashing amber lights, visible 360 degrees, shall be mounted at each end of a sign with the words “oversize load” or similar wording, on the roof of the pilot vehicle. A revolving or strobe light may be substituted for flashing lights. Lights shall be flashing at all times when piloting an oversize load.
(5) All pilot vehicles shall be equipped with two-way communication.
(6) Pilot vehicles must remain within 1,000 feet of the permitted vehicle or load.
Reference credit: Regulations and equipment for pilot vehicles as defined in ARM 18.8.510(A).
How to apply for oversize/weight trucking permits.
Montana Motor Carrier Service Division
2701 Prospect Avenue
Helena, Montana 59620
Phone: 406-444-6130 or 406-444-7262
Permits are valid for 3 days. The basic fee is $10.00
Montana frost/thaw restrictions.