Truck and trailer rules in Michigan: brakes, size limits and special permit fees

This page reports what the official source says. It is not legal advice: ask the office named here. All of the sources are sections of the Michigan Vehicle Code (1949 Public Act 300), published on the Michigan Legislature website. Federal background and the other places are on the parent page, trucks and trailers for tree work.

At a glance

Item	What the sources say
Trailer brake weight	Brakes on all wheels, applied from the cab, on a trailer or semitrailer of a gross weight of 15,001 pounds or more
Light trailers	A trailer of less than 3,000 pounds gross weight need not have brakes when two 40 percent conditions hold
Width	96 inches for the vehicle or load; 102 inches wheel to wheel on pneumatic tires
Height	13 feet 6 inches
Length	40 feet single vehicle; 59 feet truck and trailer; 65 feet truck and trailer on designated highways
Special permit fee, state roads	US$50 single trip, US$100 multiple trips or annual, as written in section 725
Licence line, carrier number	Not published on the pages read

Trailer brakes

Section 705 lists the brake equipment a vehicle must have on a highway. A trailer or semitrailer of a gross weight of 15,001 pounds or more must have brakes operating on all wheels, designed to be applied by the driver of the towing motor vehicle from its cab. For new vehicles sold in the state, brakes on all wheels are required, except that a semitrailer, pole trailer or trailer of less than 3,000 pounds gross weight need not have brakes if its gross weight does not exceed 40 percent of the gross weight of the towing vehicle when connected, with a matching condition for a semitrailer or pole trailer that rests part of its load on the towing vehicle. That subdivision does not apply to a trailer owned by a farmer and used only in farming. Every truck and truck tractor must have brakes on all wheels, with an exception for three-axle vehicles made before July 25, 1980. Every motor vehicle and combination except pole trailers, motorcycles and mopeds needs parking brakes adequate to hold on any grade where it is operated. The text sets stopping at 30 feet from 20 miles per hour for a vehicle or combination with brakes on all wheels and 40 feet where it lacks them. The pages read do not mention safety chains or a breakaway device. See section 705 on brake equipment.

Width and height

Section 717 says the total outside width of a vehicle or its load may not exceed 96 inches, with exceptions in the section. For a vehicle on pneumatic tires, the distance from the outside of one wheel and tire to the outside of the opposite one may not exceed 102 inches, and the body or load may not exceed 96 inches. A load of concrete pipe, ferrous pipe, agricultural products, or unprocessed logs, pulpwood or wood bolts may go to 108 inches. A truck and trailer or tractor and semitrailer hauling pulpwood or unprocessed logs may reach 108 inches under a special permit issued under another section. Implements of husbandry are covered by their own subsection. See section 717 on vehicle width.

Length

Section 719 sets height first: a vehicle, unloaded or loaded, may not exceed 13 feet 6 inches, and the owner is liable for damage when a vehicle strikes a lawfully established bridge or viaduct whether or not the clearance is posted. The normal length maximum for a single vehicle is 40 feet, 42.5 feet for a crib vehicle loaded with logs lengthwise and 45 feet for a single bus or motor home. A truck and semitrailer or trailer is limited to 59 feet. On a designated highway, truck and semitrailer or trailer combinations may reach 65 feet, with higher figures for combinations built to haul saw logs, pulpwood and tree length poles, which the section sets at 70 feet and, for a crib vehicle, 75 feet. See section 719 on height and length.

Special permits

Section 725 says a jurisdictional authority may issue a written special permit, on a written application with good cause shown, for a vehicle or combination whose size, weight or load exceeds the maximums in the chapter or is otherwise not in conformity. The application describes the vehicle, the load and the highways. A permit names the trips and dates it covers and may carry conditions. For the state transportation department, the section sets US$50 for a single trip and US$100 for multiple trips or an annual permit, and US$15 for a single trip and US$30 for multiple trips or annual where only size is exceeded and weight is not. The section lets the size fees rise once a year with the consumer price index, so the figure in force is on the department's own page. See section 725 on special permits.