[shadow=red,left,300]Copied from Wisconsin DMV online site.[/shadow]
(32) “Motorcycle” means a motor vehicle, excluding a tractor or an all−terrain vehicle, which is capable of speeds in excess of 30 miles per hour with a 150−pound rider on a dry, level, hard surface with no wind, with a power source as an integral part of the vehicle, and which meets the conditions under par. (a) or (b): (a) Type 1 is a motor vehicle which meets either of the following conditions: 1. Is designed and built with 2 wheels in tandem and a seat for the operator, and may be modified to have no more than 3 wheels by attaching a sidecar to one side of the wheels in tandem without changing the location of the power source. 2. Is designed and built to have no more than 3 wheels, seating for the operator and no more than 3 passengers, and does not have the operator area enclosed. (b) Type 2 is a motor vehicle designed and built to have at least 3 wheels in contact with the ground, a curb weight of less than 1,500 pounds, and a passenger and operator area with sides permanently enclosed with rigid construction and a top which may be convertible.