Wis. Stat. § 347.07: Special restrictions on lamps and the use thereof.

(1) Whenever a motor vehicle equipped with headlamps also is equipped with any adverse weather lamps, spotlamps or auxiliary lamps, or with any other lamp on the front thereof projecting a beam of intensity greater than 300 candlepower, not more than a total of 4 of any such lamps or combinations thereof on the front of the vehicle shall be lighted at any one time when such vehicle is upon a highway.

(2) Except as provided in sub. (3), or as otherwise expressly authorized or required by this chapter, no person shall operate any vehicle or equipment on a highway which has displayed thereon:

(a) Any color of light other than white or amber visible from directly in front; or

(b) Any color of light other than red on the rear; or

(c) Any flashing light.

(3) A motorcycle may be equipped with a lighting device that illuminates the ground directly beneath the motorcycle if all of the following apply:

(a) The lighting device is not visible to approaching vehicles.

(b) The lighting device does not display a red, blue, or amber light.

(c) The lighting device does not display a flashing, oscillating, or rotating light.