Frequently asked questions

IoH | Wide IoH | Ag CMV | Weight limits | State roads | Local government | Permits | Enforcement


1. What is an implement of husbandry (IoH)?

The definition of IoH is:
A self-propelled or towed vehicle manufactured, designed, or reconstructed to be used and that is exclusively used in the conduct of agriculture. An implement of husbandry may also include any of the following:

  • A farm tractor (referred to as Category A);
  • A self-propelled combine; a self-propelled forage harvester; self-propelled fertilizer or pesticide application equipment but not including manure application equipment, towed tillage, planting, and cultivation equipment and its towing power unit; or another self-propelled vehicle that directly engages in harvesting farm products, directly applies fertilizer, spray, or seeds but not manure, or distributes feed to livestock (referred to as Category B);
  • A farm wagon, farm trailer, manure trailer, or trailer adapted to be towed by or to tow or pull, another implement of husbandry (referred to as Category C).

2. Does the status of an IoH change if it is pulled by a truck?

An implement of husbandry pulled by a farm truck, motor truck, or a truck tractor, or an Ag CMV, is still an IoH. (s.340.01 (24)(a) 2, Wis. Stat.)

3. If a farm tractor is pulling planting, tillage or cultivation equipment, is it considered a Category B IoH?

Yes, a farm tractor towing tillage, planting, and cultivation equipment meets the Category B definition and as a result, it may be exempt from the axle weight limits. Please note that you may require a permit to operate over the 23,000 pound axle limit on some local roads. A permit is required to operate any IoH over the 23,000 pound axle limit on state highways.

4. Are there any height requirements required for IoH?

No, the IoH operator remains responsible for ensuring safe clearance of any overhead obstructions, like bridges and electrical wiring.

5. What are the length requirements for IoH?

IoH of the following lengths may operate on roads without a permit:

  • An IoH (single vehicle) not exceeding 60 feet in length.
  • An IoH (two-vehicle combination) not exceeding 100 feet in length.
  • An IoH (three-vehicle combination or train or a truck-drawn agricultural train) driven at a speed of 25 mph or less not exceeding 100 feet in length. An IoH three-vehicle train driven at a speed over 25 mph not exceeding 70 feet in length.

6. Are IoH with tracks allowed on Wisconsin roads?

In general, Wisconsin law does not allow tracked vehicles on the highway. This ban does not apply to implements of husbandry, including tractors and self-propelled farm equipment. IoH are allowed to operate on the road with rubber tracks, as long as it does not damage the highway. This exception was created in 1957 as part of a significant rewrite of traffic laws.

Wide IoH

1. What are the width requirements for IoH?

There are no limitations on width for IoH operated on a highway. However, lighting and marking requirements for 'wide' IoH are in place, to improve road safety for all (See the Lighting and Marking section). IoH over 8 feet, 6 inches wide being transported on interstate highways must have an oversize permit from the DOT.

During the day, an IoH operator of a 'wide' implement of husbandry has the option to use an escort vehicle instead of the lighting and marking requirements. An over-width implement used at night must always adhere to the lighting and marking requirements.

An escort vehicle with hazard lights activated is required to operate an IoH exceeding 22 feet in total width. On a two-lane road, the escort vehicle must travel in front of the IoH; for roads with two or more lanes in one direction, the escort vehicle must travel in back of the IoH.

2. The law does not place a width limitation on an IoH being operated on the roadway. In addition to the "wide implement of husbandry" equipment operating standards, are there other applicable operating statutes?

Although state law authorizes operation to the left of the centerline, provisions still require IoH to follow other laws governing the meeting, passing, and overtaking of vehicles encountered on the road.

  • An operator of an IoH is still required to give at least one-half of the main traveled portion of the road when meeting another driver on a two-lane road.
  • An IoH shall not be driven left of the centerline upon any grade or curve or when their view is obstructed for such a distance as to create a hazard, which includes a no-passing zone.
  • Operation of an IoH typically is traveled at low speeds. There is no change to the statute typically referred to as "impeding traffic." The operator of any vehicle must yield to other traffic when operating below a speed considered to be normal and reasonable based on the conditions present.


1. What is an Agricultural Commercial Motor Vehicle?

An Ag CMV is a commercial motor vehicle to which all of the following apply:

  • Substantially designed or equipped, or materially altered from its original construction, for the purpose of agricultural use
  • Designed and manufactured primarily for highway use
  • Manufactured to meet federal motor vehicle safety standard certification label requirements 49 CFR 567, after 1970
  • Used exclusively in the conduct of agricultural operations
  • Directly engaged in harvesting farm products, directly applies fertilizer (including manure), spray or seeds to a farm field, or distributes feed to livestock

2. Is a "semi-tractor / semitrailer combination" or "motor truck / trailer" combination considered an Ag CMV?

The power unit and the towed unit are considered two separate vehicles which make up a combination vehicle. Each vehicle in the combination must meet the definition of an Ag CMV independently for that single vehicle to be considered an Ag CMV. In the case of a tractor-semitrailer combination, the semitrailer portion of the combination is more likely to be the Ag CMV. The truck tractor in most cases will not meet the definition of an Ag CMV. (Wis. Stat. 340.01(8) & 340.01(1o))

There are situations when a truck tractor will not meet the definition of an Ag CMV but the semitrailer will. In those cases, the truck tractor would not be exempt from registration. The semitrailer, if an Ag CMV, would be exempt from registration. In this scenario, the Ag CMV weight limits would be applied to the tractor-semitrailer combination. (Wis. Stat. 348.15(3)(g))


  • “Motor truck” means every motor vehicle designed, used or maintained primarily for the transportation of property. (Wis. Stat. 340.01(34))
  • “Semitrailer” means a vehicle of the trailer type so designed and used in conjunction with a motor vehicle that some part of its own weight and that of its own load rests upon or is carried by another vehicle. (Wis. Stat. 340.01(57))
  • “Tractor−semitrailer combination” means a combination of 2 vehicles consisting of either a truck tractor and a semitrailer or a road tractor and a semitrailer. (Wis. Stat. 340.01(67r))
  • “Trailer” means a vehicle without motive power designed for carrying property or passengers wholly on its own structure and for being drawn by a motor vehicle, but does not include a mobile home. (Wis. Stat. 340.01(71))

  • “Truck tractor” means a motor vehicle designed and used primarily for drawing other vehicles and not so constructed as to carry a load other than a part of the weight of the vehicle and load so drawn. (Wis. Stat. 340.01(73))

3. Are there any height restrictions for​ Ag CMVs?

Yes, Ag CMVs are still subject to the height restriction for regular CMVs under current law, which is 13'6".

4. What are the length limits for Ag CMV?

An Ag CMV needs a permit if it exceeds these limits:

  • An Ag CMV (single vehicle) may not exceed 45 feet in length.
  • Standard limits for an Ag CMV (two-vehicle combination) is 70 feet in length. There are some instances in which an Ag CMV combination vehicle may be 75 feet in length. You are advised to contact the permit unit to discuss your options.
  • An Ag CMV (three-vehicle combination or train or a truck-drawn agricultural train) driven at a speed of 25 miles or less may not exceed 100 feet in length. An Ag CMV three-vehicle train driven at a speed over 25 miles per hour, may not exceed 70 feet in length.

5. What are the width requirements for Ag CMV?

An Ag CMV is limited to 10 feet in width including all accessories or attachments. The tires, fenders or fender flares of Ag CMVs spraying pesticides or spreading lime or fertilizer (not manure) may extend up to 12 feet.

IoH/Ag CMV weight limits

1. What are the weight requirements for IoH and Ag CMVs?

The weight limit for all IoH and Ag-CMVs is 15% higher than the federal bridge formula. This equates to a maximum single axle weight of 23,000 pounds and maximum gross vehicle weight (GVW) of 92,000 pounds, dependent on axle number and spacing as presented in the IoH/Ag CMV Maximum Weight Limits table (s. 348.15 3g).

2. What about posted roads and bridges?

  • Category B IoH can disregard Class B postings of roads (s. 348.16 (2))
  • All IoH, including Category B, MUST OBEY seasonal or special weight posting or bridge posting (348.17)

3. Are there any other exemptions from the weight limits?

There are exemptions for certain types of vehicles and certain types of roads:

  • Category B IoH (see definition above) must adhere to the 92,000 pound GVW, but may be exempt from axle weight limits. Category B is also exempt from the weight and size limitations for crossing a roadway or incidental travel from farm to field or field to field ½ mile or less.
  • Empty potato harvesters are exempt from axle weight limits, but are subject to the 92,000 pound GVW. Potato harvesters are required to have one or more escort vehicles with hazard lights on if traveling more than 1/2 mile.

4. Do IoH/Ag CMV weight limits apply to Interstate highways?

The weight limits are not allowed on Interstate highways. However, I-41 corridor travel (s. 348.01 (2)(bd, Wis Stat.) is exempted from this provision.

5. Do IoH/Ag CMV weight limits apply to state highways?

The state requires a permit to operate any IoH or Ag CMV on a state highway with an axle weight over 23,000 pounds or a gross vehicle weight of 92,000 pounds.

State roads

1. Do IoH/Ag CMV weight limits apply to state highways?

For state highways, a state no-fee permit is required for any IoH with an axle weight over 23,000 pounds or a gross vehicle weight of 92,000 pounds – including Category B IoH.

Local governments

1. Do local governments have local control?

Yes, towns, counties, and the state have their respective authorities to issue permits and post roads and bridges as they have under prior law. Local governments have a range of choices to implement the IoH/Ag CMV laws and laws have created a uniform no-fee permit application.

2. Are local governments required to participate in the no-fee permitting process?

Maintaining authorities have several options under the law. Communities who do not wish to issue any permits may pass an ordinance or resolution granting IoH and Ag CMVs unlimited weight and length operation within their jurisdiction. There are no limits for height and width for IoH.

All other maintaining authorities are required to participate in the permitting process.

Local governments may choose to:

  • Allow all IoH and Ag CMVs to operate without a permit according to the IoH/Ag CMV weight table and gives Category B IoH an exemption from the axle weight limit of 23,000 pounds
  • Post roads or bridges in their jurisdiction
  • Pass an ordinance or resolution to:
    • Set a higher weight limit than in the IoH/Ag CMV Weight Table for all roads in their jurisdiction
    • Designate some roads for overweight IoH or Ag CMV travel
    • Require all IoH (including Category B) or Ag CMV to follow the IoH/Ag CMV Maximum Weight Table Limits for GVW and axle weight and get a permit

Ordinances or resolutions must be passed by November 30 of each calendar year.

It is important to note that all IoH and Ag CMV operation is still subject to seasonal or special postings for roads and structures.

3. Can a local government give a permit to operate over the weight limit of a posted bridge?

No, all IoH, including Category B, MUST OBEY seasonal or special weight posting or bridge posting.


1. How much will an IoH/Ag CMV permit cost?

It is a no-fee permit. Law specifically prohibits municipalities and counties from charging a fee for the IoH/Ag CMV permit. It also prohibits them from charging a fee for any study, investigation, or other review in connection with an application for the no-fee permit.

2. When do no-fee permits go into effect?

The no-fee permit provisions are now in effect. Operators who have an IoH or Ag-CMV which exceeds the weight and/or length limits are encouraged to contact their local road authority to discuss operation. A permit is required to operate on state highways over the length and axle and gross vehicle weight limits.

3. How will the no-fee permit application work for IoH and Ag CMV outside the size and weight envelope?

The Department of Transportation has a no-fee permit application available on their website, along with a list of the points of contact for local government offices.

The application must list all of the oversized implements the applicant wishes to operate, and include a listing or map of roadways the applicant plans to use for the year. Remember, the no-fee permit is only required for equipment outside the length and weight limits.

4. What is the timeline for the permit processing?

After the maintaining authority receives the permit application, they have three weeks to respond with approval or denial, or the application is presumed approved. If the maintaining authority has not responded within six weeks, the application is approved.

5. What if I get a new piece of equipment during the year?

If the applicant needs to amend their application, the maintaining authority has five days to respond with approval or denial, or the amendment is presumed approved. If the maintaining authority has not responded to the amendment within ten days, the amendment is approved.

6. How long is the permit valid?

The no-fee permit is valid for at least one year, but can be renewed annually after the first year of submission for subsequent calendar years. Towns and Counties can choose to make the permit last for longer than a year. The permit issued by the State for operation on state roads automatically renews annually until DOT revokes the permit or the applicant amends it.

7. What if the maintaining authority denies the routes included in my no-fee permit application?

Any denial must be provided in writing and give a reasonable, structurally-based explanation as to why the road or section of road cannot be used. If the application is made for a Category B IoH, the denial must include an approved alternative highway route or map of highways for operation.

Further, if the person or governmental maintaining authority responsible denies the application, the applicant will have the ability to appeal the decision through an administrative review process to that person's governmental unit. For example, if the town chairman denies the application, the applicant would appeal the denial to the town board. At the county level, the applicant would appeal to the county highway committee.

Applicants also have the option of bypassing the administrative review process and directly filing an action in circuit court challenging the adverse decision.

8. If my IoH or Ag CMV doesn't meet the axle requirements but does meet the overall weight requirements, am I still required to submit the no-fee permit application?

A permit is required to operate over the 23,000 pound axle limit on state highways. Towns and counties have several options in applying this law. Please check with your local road authority.


1. Should applicants expect enforcement of weight regulations and what are the penalties?

IoH and Ag CMVs regulations are current law and violators may be issued citations. Fines are determined by weights defined in the weight table in s. 348.15(3)(c), Wis. Stat. If found in violation, operators must return their vehicles to legal weight to proceed.

2. Will lighting and marking regulations be enforced?

Yes, lighting and marking requirements for IoH, including wide IoH, are current law and will be enforced.

3. Is a skid steer used exclusively in the conduct of agricultural operations considered an IoH or Ag CMV?

No, a skid steer is considered “road machinery”, as defined in s. 340.01(52), Wis. Stats., regardless of its use. (§ 340.01 Annotation)


For questions and information on IoH and Ag CMV:

Wisconsin Department of Transportation
Bureau of Highway Maintenance
P.O. ​Box 7980
Madison WI 53707-7980

Phone (608) 266-7320