Wis. Stat. § 346.925: Operation of agricultural machinery by youthful operators.

(1) No person may direct or permit a child under the age of 16 years to operate a farm tractor or self-propelled implement of husbandry on the highway unless the child has been certified under s. 36.25 (32) (a) 2. as successfully completing a tractor and machinery operation safety training course that is equivalent to the requirements, other than age, specified under 29 CFR 570.70 to 29 CFR 570.72.

(2) Subsection (1) does not apply to operation of a farm tractor or self-propelled implement of husbandry on the highway on a course that is perpendicular to the direction of the highway.