Truck and trailer rules in Wisconsin: licence classes, brakes, size limits and the vehicle equipment code

This page reports what the official source says. It is not legal advice: ask the office named here. All of the sources are chapters of the Wisconsin Statutes and the Wisconsin Administrative Code, published by the Wisconsin Legislature. 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
Commercial motor vehicle	Single vehicle rated 26,001 pounds or more, or registered or actual gross weight over 26,000 pounds; combination of 26,001 pounds or more that includes a towed unit over 10,000 pounds
Class A	Combination over 26,000 pounds when the towed vehicles together are over 10,000 pounds
Class B	Single vehicle over 26,000 pounds, including towing 10,000 pounds or less
Class C	26,000 pounds or less, only for 16 or more passengers or placarded hazardous materials
Trailer brakes	Required on a trailer or towed vehicle of 3,000 pounds gross weight or more; towing exception at 40 percent of the towing vehicle's gross weight
Stopping distance	50 feet from 20 miles per hour for a motor vehicle or combination
Width, height	8 feet 6 inches wide; 13 1/2 feet high, without a permit
Length	45 feet single vehicle; 70 feet for a two-vehicle combination, without a permit
Carrier number	Not published on the pages read

Definitions and licence classes

Section 340.01 defines a commercial motor vehicle as a motor vehicle designed or used to transport passengers or property that meets one of four descriptions. The first is a single vehicle with a gross vehicle weight rating of 26,001 or more pounds, or a registered weight or actual gross weight of more than 26,000 pounds. The second is a combination with a gross combination weight rating, registered weight or actual gross weight of 26,001 or more pounds that includes a towed unit with a rating, registered weight or actual gross weight of more than 10,000 pounds. The third is a vehicle built for the driver and 15 or more passengers. The fourth is a vehicle carrying placarded hazardous materials. See section 340.01 on definitions.

Section 343.04 sorts motor vehicles into licence classes. Class A is any combination with a rating, actual gross weight or registered weight of over 26,000 pounds when the vehicles being towed add up to more than 10,000 pounds. Class B is a single vehicle over 26,000 pounds, and that vehicle towing 10,000 pounds or less. Class C is a single vehicle of 26,000 pounds or less, including one towing less than 10,000 pounds, when it is built to carry 16 or more passengers or carries placarded hazardous materials. Class D is any motor vehicle not in the other classes, and class M is a motorcycle. The section also lists vehicle types such as full air brakes equipped, partial air brakes equipped and vehicles towing double or triple trailers. See section 343.04 on vehicle classifications.

Brakes

Section 347.35 says a motor vehicle other than a moped or motorcycle must have brakes adequate to control, stop and hold it, with two separate means of applying them, each effective on at least two wheels. Every such vehicle and combination needs parking brakes that hold on any grade where it operates, under all conditions of loading. For trailers, the section says a trailer, semitrailer or other towed vehicle with a gross weight of 3,000 pounds or more, made after January 1, 1942, must have brakes adequate to control, stop and hold it. A motor vehicle may be towed without brakes when its gross weight is not more than 40 percent of the towing vehicle's gross weight and the towing vehicle's brakes can stop the combination as section 347.36 requires. Farm trailers and disabled vehicles being towed to a place of repair are outside the subsection. The pages read do not mention a breakaway device or safety chains by those names. See section 347.35 on brakes.

Section 347.36 sets the performance line: brakes on a motor vehicle and on a combination must be able to stop it, under normal conditions, within 50 feet when travelling at 20 miles per hour, and required brakes must be kept in good working order. The cross-reference at the foot of section 347.35 points to chapter Trans 308 and to sections of chapter Trans 305 of the Administrative Code. Trans 305 is titled standards for vehicle equipment, with a subchapter for automobiles, motor homes and light trucks and another for heavy trucks, trailers and semitrailers. See chapter Trans 305 on vehicle equipment standards.

Width, height and length

Section 348.05 says no one without a permit may operate a vehicle wider than 8 feet 6 inches, with a list of exceptions for vehicles such as implements of husbandry and snowplows. Section 348.06 sets the height line at 13 1/2 feet overall for a motor vehicle, mobile home, recreational vehicle, trailer or semitrailer. Section 348.07 sets the length line at 45 feet for a single vehicle and 70 feet for a combination of two vehicles, then lists longer limits, among them 48 feet for a semitrailer or trailer in a two-vehicle combination and 75 feet for a tractor-semitrailer combination. Section 348.08 covers vehicle trains and says no one without a permit may operate a motor vehicle drawing more than one vehicle, apart from the listed exceptions. See section 348.07 on length of vehicles and section 348.05 on width.