Highway types

State roadways have use restrictions placed on them by the Michigan Department of Transportation (MDOT) for use by commercial motor vehicles. Restrictions are based on vehicle size and the time of year, and are depicted in the MDOT Truck Operators' Map. The map depicts state roadways (designated or non-designated routes) in various colors and explains their particular use:

• Green Routes - Special Designated Highway (increases size and weight provisions; all weather/all seasonal)
• Gold Routes - Same as the green; also designated as National Truck Network routes
• Black Routes - Open to legal axle loads and normal length/width limitations year round (same as green for weight)
• Red Routes - Seasonal routes (same as black for length/width). Subject to weight limitations during the spring as noted below:

Vehicle length
See MVC 257.719 for complete definition
The total distance from the front of a vehicle, or combination of vehicles, to the rear of the vehicle or combination of vehicles, including the distance of any load being transported on the vehicle

Load projections
See MVC 257.791

• A load may not project more than three feet beyond the front of the vehicle provided the length of the vehicle and load do not exced the maximum allowable vehicle length
• Any amount of overhang from the rear of the vehicle is allowable as long as the legal load length is not exceeded

FMCSR 393.11 (Footnotes 9 & 10) and 393.87 require a load that extends more than four feetfrom the rear of ta vehicle and/or 4 inches from the side, shall be marked with additional clearance lamps and 12-inch square red flags square flags at all times.

Length shall not include safety and energy conservation devices. Such a device shall be excluded from a determination of length as long as it is not designed or used for the carrying of cargo.

A rear overhang of six feet is permissible for trailers with a length of 50 feet or less if the trailer is designed and used to transport saw logs, pulpwood or tree-length wooden poles.

Special permits

Vehicles or loads which exceed legal dimensions or weight require a special permit when operating on U.S. Highways. For permit information, contact the Michigan Department of Transportation at (517) 373-2120.

Single vehicle
With or without load (excluding impact absorbing bumpers) 40 feet - all routes

Tractor, semitrailer
Tractor, semitrailer combinations have no overall length restrictions, provided the trailer length does not exceed 50 feet.

On designated routes, tractor and semitrailer combinations have no overall length restrictions, provided the trailer does not exceed 53 feet in length and has no more then two axles.

Semitrailers longer than 50 feet shall have a wheel base of not less than 37.5 feet and not more than 40.5 feet (plus or minus .5 feet), measured from the kingpin coupling to the center of the rear axle or the center of the rear axle assembly if equipped with two or three axles.

Note: City, village or county authorities may prohibit stops of vehicles with a semitrailer longer than 50 feet within their jurisdiction unless the stop occurs along appropriately designated routes, or is necessary for emergency purposes or to reach shippers, receivers, warehouses and terminals along designated routes.

Truck and trailer

• 59 feet overall length on non-designated routes
• 65 feet overall length on designated routes
• 70 feet (including the load) on designated routes if the vehicles are designed and used to transport saw logs, pulpwood or tree length wooden poles

Tractors, semitrailer and trailer or two semitrailers

• Non-designated routes - 59 feet overall length
• Designated routes - no overall length if:
  • The length of each trailer or semitrailer does not exceed 28.5 feet in length or
  • The overall length of the trailers in combination does not exceed 58 feet, measured from the front of the first trailer to the rear of the second trailer

• 55 feet on non-designated highways
• 75 feet on designated highways

Mobile homes
MVC 257.719

• Body length (not including tongue) - 45 feet if the body is not more than 12.5 feet in height and not more than 102 inches wide at base rail
• 60 feet overall length when in combination with a towing unit
• Mobile homes which exceed these dimensions must be moved under a special permit issued by the Michigan Department of Transportation

Vehicle height
MVC 257.719

A vehicle unloaded or with a load (except mobile homes) shall not exceed a height of 13 feet, 6 inches without special permit.

Mobile homes may not exceed a height of 12 feet, 6 inches without special permit.

Vehicle width
MVC 257.717

• The total outside width of a vehicle or the load on a vehicle shall not exceed 96 inches
• The total outside width of a vehicle or the load on a vehicle shall not exceed 102 inches on designated routes
• The total outside width of the load of a vehicle hauling concrete pipe, agricultural products or unprocessed logs, pulpwood or wood bolts shall not exceed 108 inches
• The total outside width of a bus or motor home shall not exceed 102 inches

County and local municipalities may have size and weight restrictions that differ from those described in the Truck Driver's Guidebook and the Michigan Vehicle Code.

Q. What do I need if I exceed vehicle size and/or weight limits?

A. You will need a size/weight permit issued from MDOT and possibly from the counties you might travel. Be sure to read all conditions and restrictions of the permit. Failure to comply with those conditions and restrictions may void the permit. Also, be aware of the light and flag requirements of FMCSR 393.11. Requirements of 393.11 may apply even without exceeding vehicle size and weight limits.

For more frequently asked questions,
go to www.truckingsafety.org.

Table of Contents

For permit information, contact the
Michigan Department of Transportation at
(517) 373-2120

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.