Implements of Husbandry (IoH) and Agricultural Commercial Motor Vehicles (Ag CMVs) are how WisDOT refers to tractors, trailers and other vehicles that are used for agricultural work. Recognized as essential tools in the agricultural industry, these vehicles are allowed to operate on roadways. However, this equipment is heavy and poses risks to bridges and pavements. These vehicles are big and can be difficult to maneuver as well, which creates safety concerns. Laws regulating IoH and Ag CMVs on the roads promote public safety and help protect our infrastructure.
Higher Weight Limits
In general, IoH and Ag CMVs are allowed to operate at 15 percent higher weight limits than the federal bridges formula. Agricultural weight limits are 23,000 pounds per axle or 92,000 pounds gross vehicle weight (GVW), dependent on number of axles and axle spacing, and subject to seasonal or special postings. Certain IoH may be given an axle weight exemption on local roads. These higher weight limits are not allowed on interstate highways, though I-41 is grandfathered to allow these weights.
WisDOT and local authorities can issue a “no-fee permit” which allows an operator to ride on certain routes at even higher weights or a longer length than provided by law. These permits provide WisDOT and local authorities an opportunity to track the weights that road pavements and bridge spans receive. This information can be used to better protect and plan for our shared roadways.
Local Government Authority
WisDOT maintains state highways and bridges. Local governments - counties, cities, towns and villages - maintain their own roads. Wisconsin law provides these local governments authority to set weight limits for IoH and Ag CMVs, if they so choose. IoH and Ag CMV operators must check what regulations, if any, their local governments have in place. WisDOT publishes these regulations on the Local government information webpage. This page also has resources for local governments on IoH/Ag CMV regulation.
Lighting and Marking Requirements
IoH and Ag CMVs are common sights on Wisconsin roads. Still, drivers often don't realize that these vehicles are slower, less agile, and much larger than standard vehicles. Lighting and marking requirements draw attention to the size, shape, and speed of agricultural vehicles and alert drivers that caution is required. All IoH have lighting and marking requirements, but Wisconsin has specific lighting and marking requirements for "wide" IoH, defined as equipment that is 15 feet and wider. Roads in Wisconsin have diverse users and everyone has a responsibility for safety.
Use these webpages to:
- Determine what category of vehicle you operate (IoH and Ag CMV pages).
- Review the weight table for your vehicle's specific gross vehicle and axle weight limits.
- Learn why axle weights matter.
- Check the list of local governments who have passed resolutions and ordinances regarding restrictions on roads in their jurisdiction.
- Apply for a No Fee Permit, from WisDOT, your local maintaining authority, or both, to operate your equipment on the specific route you've identified.
- Review the Ag vehicle safety webpage for information on IoH Lighting and Marking requirements and road safety.