Implements of Husbandry rules

New implements of husbandry (IoH) regulations will take effect November 1, 2015. Many pieces of farm machinery have already been manufactured with the lighting and marking requirements that are now reflected in Wisconsin law.

Download the helpful IoH Lighting and Marking Brochure.

What is a wide IoH?
Any IoH exceeding 15 feet in total width or that extends over the center of the roadway into a lane intended for the opposite direction of travel. Width is determined by the widest measurement of the equipment in a highway transport configuration.

A town road may have a roadway of 18 feet. This means at 9 feet, an IoH vehicle or vehicle combination meets the definition of a wide IoH. Standard lane width for a county or state roadway with a marked center-line is 11 feet. It is important to know your route and roadway factors that may require additional considerations for wide IoH.

Wide IoH must have:

  • At least 2 amber flashing warning lamps, visible from both the front and rear. Must be mounted, as nearly as practicable, to indicate the extreme width but not more than 16 inches from the lateral extremities.
  • Red retroreflective material, visible to the rear and mounted within 25 inches of the extreme left and extreme right of the IoH, spaced as evenly as practicable.
  • At least 2 strips of yellow retroreflective material visible to the front. On left and right sides of IoH, the outer edge of this material shall be mounted within 16 inches of the extreme left and extreme right of the IoH.
  • At least 2 red tail lamps mounted to the rear of the IoH, or as close to the rear as practicable. These lamps are not required to be wired to light when headlamps or other lamps are activated. This provides for the use of battery powered tail lamps.
  • A slow-moving vehicle (SMV) emblem.


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