Wisconsin Statutes & Annotations
Chapter 347 - Equipment of vehicles.
347.46 - Fenders and mudguards.

347.46 Fenders and mudguards.
(1) No person shall operate a vehicle of the tractor type on a highway unless the driving wheels of such vehicle are protected by suitable fenders.
(2) No person shall operate on a highway in intercity movement any privately owned motor truck or privately owned semitrailer drawn by a truck tractor, except those motor trucks and semitrailers equipped with dump bodies, unless such motor truck or semitrailer is equipped with rear fenders or mudguards of such material and so constructed and placed as to restrict to a minimum the splashing of water, mud or other material which may be thrown by the rear wheels. Such rear fenders or mudguards shall meet the following minimum specifications:
(a) The fenders or mudguards shall cover the tire or multiple tires they are protecting starting at the top from a line drawn vertically through the center of the axle and extending rearward and downward so that the fender or mudguard under any condition of operation or loading of the vehicle has a ground clearance of not more than one third of the horizontal distance from the center of the rearmost axle to the fender or mudguard;
(b) The fenders or mudguards shall be at least as wide as the tire or multiple tires they are protecting;
(c) If the vehicle is so designed and constructed that the rear wheels are covered in the manner specified in pars. (a) and (b) by means of fenders, body construction or other means of enclosure, then no special mudguards are required. Otherwise, the vehicle shall be equipped with special mudguards to the extent necessary to meet the requirements of pars. (a) and (b).

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