Vehicle and Load Size

Michigan Weight and Axle Load Limits

Due to frequent changes in federal and state regulations, the Michigan Center for Truck Safety cannot ensure the accuracy of the material

contained in the Guidebook beyond the date of publication. For current information, contact the Center at (800) 682-4682. This document is not

intended for legal purposes.

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MAXIMUM LEGAL TRUCK LOADINGS AND DIMENSIONS

Regulations pertaining to the operation of trucks and trailers according to Act 300 P.A. 1949 as amended.

NOTE : When restricted loadings are in effect, the normal maximum axle weights allowable

on rigid pavements shall be reduced 25% and the maximum wheel load shall not

exceed 525 pounds per inch width of tire. When restricted loadings are in effect,

the normal maximum axle weights allowable on flexible pavements shall be reduced

35% and the maximum wheel load shall not exceed 450 pounds per inch width of tire.

MAXIMUM OVERALL DIMENSIONS

Width ................................................................................................................................................................................................. 96 inches

Width (designated highways) ........................................................................................................................................................... 102 inches

Height .......................................................................................................................................................................................13 feet, 6 inches

Length of semitrailer (including load)................................................................................................................................................53 feet

Length of a semitrailer (including load) NONDESIGNATED HIGHWAY............................................................................................50 feet

Length of combination of truck-tractor and semitrailer with or without load .................................................................................. No limitation

Length of any other vehicle with or without load (excluding impact absorbing bumpers).................................................................... 40 feet

Units permitted in train...............Truck-tractor, semitrailer and trailer or truck- tractor and 2 semitrailers or truck and semitrailer or trailer.

Length of a combination of truck-tractor, semitrailer, and trailer or truck-tractor and 2 semitrailers or truck and semitrailer or trailer with or

without load or pickup truck, semitrailer designed for recreational living purposes, and additional trailer or semitrailer (see exceptions)

......................................................................................................................................................................................................... 65 feet

Semitrailers longer than 50 feet shall have a wheelbase of 37 feet to 41 feet (measured from the kingpin coupling to the center of the

axles or to the center of the tandem axle assembly if equipped with 2 axles).

Semitrailers longer than 50 feet are limited to 3 axles.

Semitrailers longer than 50 feet shall operate on designated highways only.

Semitrailers and trailers shall be measured from the front vertical plane of the foremost transverse load supporting structure to the rearmost

transverse load supporting structure.

Length shall not include safety and energy conservation devices including, but not limited to, impact absorbing bumpers, rear view mirrors,

turn signal lamps, marker lamps, steps and hand holds for entry and egress, flexible fender extensions, mud flaps or splash and

suppressant devices, load induced tire bulge, refrigeration or heating units, or air compressors. A device shall be excluded from a

determination of length only if it is not designed or used for the carrying of cargo.

Projection beyond front of vehicles .................................................................................................................................................. 3 feet

Overhang beyond rear of vehicles ................ Any amount is permissible if the legal length is not exceeded. However, if this overhang is

4 feet or more, there shall be displayed on the extreme rear of such a load a 12 - inch red square flag in the daytime and a red light or

lantern at night.

Axle limitation ............................................................................................................... A combination of vehicles shall not exceed 11 axles.

EXCEPTIONS:

WIDTH: Unprocessed Logs, Pulpwood, Wood Bolts, Agricultural Products, and Concrete Pipe, (108 inches for load only), Busses,

(102 inches), Implements of Husbandry: A person may only operate or tow an implement of husbandry of any width on a highway as

required for normal farming operations.

LENGTH: Truck-Tractor, Semitrailer, and Trailer or Truck-Tractor and 2 Semitrailers: No overall length limitation providing the

length of each semitrailer and trailer including load does not exceed 28 feet 6 inches or the overall length of the semitrailer and trailer or

2 semitrailers as measured from the front of the first towed unit to the rear of the second towed unit while the units are coupled together

does not exceed an overall length of 58 feet, including load. Any such combination, except as herein described with regard to assembled

motor vehicles or bodies, recreational vehicles or boats, may be operated only on such highways and routes as designated by the

appropriate authorities.

Truck and Trailer or Semitrailer: Overall length not to exceed 65 feet. Any such combination may be operated only on such highways

and routes as designated by the appropriate authorities.

Truck and Trailer or Semitrailer: Designed and used to transport saw logs, pulpwood, and tree length poles. Overall length is not to

exceed 70 feet including load. Any such combination may be operated only on such highways and routes as designated by the appropriate

authorities.

Truck-Tractor, Semitrailer, and Trailer, or Truck Tractor and Semitrailer or Trailer designed and used exclusively to transport

assembled motor vehicles or bodies, recreational vehicles, or boats: Any such combination not to exceed a total length of 65 feet,

except a stinger-steered combination shall not exceed a total length of 75 feet. The load on any such combination of vehicles may extend

an additional 3 feet beyond the front and 4 feet beyond the rear of the combination of vehicles.

Articulated Busses: Articulated busses operated by a local public transit system funded by Act No. 51 of the Public Acts of 1951, as

amended, may operate with a maximum length of 65 feet.

MAXIMUM OVERALL DIMENSIONS CONTINUED.......

Motor vehicles wholly or partially assembled transported by utilizing 1 tow bar or 3 saddle mounts with full mount mechanisms

and using the motor power of 1 vehicle. Any such combination of vehicles may not exceed the maximum length of 75 feet. Any

combination that exceeds 55 feet in length may be operated only on such highways and routes as designated by appropriate authorities.

The total gross weight of any 65-foot combination of vehicles shall not exceed a ratio of 400 lbs. per engine net horsepower delivered to

clutch or its equivalent specified in the SAE test code.

MOBILE HOMES: 45 feet in body length, 60 feet when in combination with a towing unit 8 feet 4 inches in width, 12 feet 6 inches in height.

VEHICLES TRANSPORTING FLAMMABLE LIQUID, IN BULK, WHICH AS A FLASH POINT AT OR BELOW 70 DEGREES FAHRENHEIT:

Vehicles shall meet safety standards as determined by the Department of State Police. Vehicles manufactured after July 27, 1978,

are limited to 11 feet 8-1/2 inches maximum height.

Spacings Between Normal Loadings When Seasonal Load Seasonal Load Limitations

Axles Limitations Are Not In Force (Speed Limit 35 MPH)

(Speed Limit 55 MPH)

Vehicles Exceeding Vehicles 80,000 lbs. Rigid Flexible

80,000 lbs. Gross Or Under Gross

Weight Weight

9 feet or over 18,000 lbs. 20,000 lbs. 13,500 lbs. 11,700 lbs.

More than 3 ½ feet but, less than 9 feet 13,000 lbs. 13,000 lbs. 9,750 lbs. 8,450 lbs.

When part of a tandem axle assembly *16,000 lbs. 34,000 lbs. on tandem **12,000 lbs. ***10,400 lbs.

When less than 3 ½ feet 9,000 lbs. 9,000 lbs. 6,750 lbs. 5,850 lbs.

Maximum load on any wheel shall not

exceed: (lbs. per inch of tire width) 700 lbs. 700 lbs. 525 lbs. 450 lbs.

Gross vehicle weight may not exceed 80,000 lbs. and the following: An overall gross weight on a group of 2 or more consecutive

axles equaling:

( LN )

W = 500 ( — + 12N + 36 )

( N - 1 )

Where W = overall gross weight on a group of 2 or more consecutive axles to the nearest 500 pounds,

L = distance in feet between the extreme of a group of 2 or more consecutive axles, and

N = number of axles in the group under consideration; except that 2 consecutive sets of tandem axles may carry a gross load of 34,000

lbs. each if the first and last axles of the consecutive sets of tandem axles are not less than 36 feet apart, and the gross vehicle

weight does not exceed 80,000 lbs. including all enforcement tolerances. Except for 5-axle truck tractor, semitrailer combinations

having 2 consecutive sets of tandem axles, vehicles having a gross weight in excess of 80,000 lbs. or in excess of the vehicle gross

weight determined by application of the formula in this subsection shall be subject to the maximum axle loads specified in column

2 (Normal Loadings When Seasonal Load Limitations Are Not In Force).

A vehicle or combination of vehicles, when utilizing an additional 5 miles from a “Special Designated Highway” for access to or from

points of origin or destination, must reduce to the following weights when the route being traveled is under seasonal load limitations:

Rigid route - 15,000 lbs. on a single axle, 12,750 lbs. per axle on a tandem axle assembly. Flexible route - 13,000 lbs. on a single

axle, 11,050 lbs. per axle on a tandem axle assembly.

* On any legal combination of vehicles, only one (1) tandem axle assembly shall be permitted at the gross weight of 16,000 lbs. per

axle and no other tandem axle assembly in such combination of vehicles shall exceed a gross weight of 13,000 lbs. per axle. When the

gross weight of a combination of vehicles with a load does not exceed 80,000 lbs., two (2) tandem axle assemblies shall be permitted at

a gross weight of 16,000 lbs. per axle.

** On any legal combination of vehicles, only one (1) tandem axle assembly shall be permitted at the gross weight of 12,000 lbs. per

axle and no other tandem axle assembly in such combination of vehicles shall exceed a gross weight of 9,750 lbs. per axle. When the

gross weight of a combination of vehicles with a load does not exceed 80,000 lbs., two (2) tandem axle assemblies shall be permitted at

a gross weight of 12,000 lbs. per axle.

*** On any legal combination of vehicles, only one (1) tandem axle assembly shall be permitted at the gross weight of 10,400 lbs. per

axle and no other tandem axle assembly in such combination of vehicles shall exceed a gross weight of 8,450 lbs. per axle. When the

gross weight of a combination of vehicles with a load does not exceed 80,000 lbs., two (2) tandem axle assemblies shall be permitted at

a gross weight of 10,400 lbs. per axle.

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TABLE OF MAXIMUM ALLOWABLE GROSS AXLE LOADINGS

Truck, or a Truck and Trailer, or a Truck-Tractor and Semitrailer: Movement not allowed transporting a quantity of more than 9,000

gallons within a county having a population of 600,000 or more, except between the hours of midnight to 6:00 a.m. on routes and times

designated by the Department of State Police.

Truck-Tractor, Semitrailer and Trailer or Truck-Tractor and 2 Semitrailers: Movement is not allowed within a county having a

population of 600,000 or more except between the hours of midnight to 6:00 a.m. on routes and at times designated by the Department

of State Police.