(a) Every motor carrier, motor vehicle, truck, semitrailer, and trailer shall be equipped with pneumatic tires of sufficient traction surface in accordance with the capacity of the motor carrier or motor vehicle, except as otherwise herein provided, the same to be prescribed by the Director of Public Safety.

(1) No person shall operate any vehicle of a type required to be licensed upon the highways of this state except for those tires on the dead axle of a vehicle with a dead axle when one or more of the tires in use on such vehicle is in unsafe operating condition or has a tread depth less than 2/32 inch or .15875 centimeters measured in any two adjacent tread grooves at three equally spaced intervals around the circumference of the tire; provided, that such measurements shall not be made at the locations of any tread wear indicator. A tire shall be considered unsafe if it has any part of the ply or cord exposed, any bump, bulge, or separation, any tread or sidewall cracks, cuts, or snags in excess of one inch in length and deep enough to expose the body cords, any tire marked "not for highway use," or "for racing purposes only," or "unsafe for highway use" or words of similar import and any tire which has been regrooved or recut below the original groove depth, excepting special tires which have extra undertread rubber for this purpose and are identified as such; provided, that the prohibitions of this section shall not apply to the tires upon the dead axle of a vehicle equipped with such a dead axle.

(2) No person, firm, corporation, or organization shall sell or offer for sale tires, or a vehicle equipped with tires, for use upon the highways of this state, which are in unsafe condition or which have a tread depth of less than 2/32 inch or .15875 centimeters measured as specified in subdivision (1) of this subsection.

(b) No tire on a vehicle moved on a highway shall have on its periphery any block, stud, flange, cleat, or spike or any other protuberances of any material other than rubber which project beyond the tread of the traction surface of the tire, except that it shall be permissible to use farm machinery with tires having protuberances which will not injure the highway and, except also, that it shall be permissible to use tire chains or metal studded or safety spike tires of reasonable proportions upon any vehicle when required for safety because of snow, rain, or other conditions tending to cause a vehicle to slide or skid.

(c) Every solid rubber tire on a vehicle moved on any highway shall have rubber on its entire traction surface of at least four inches and one inch thick above the edge of the flange of the entire periphery.

(d) The Department of Public Safety and local authorities in their respective jurisdictions may, in their discretion, issue special permits authorizing the operation upon a highway of traction engines or tractors having movable tracks with transverse corrugations upon the periphery of such movable tracks or farm tractors or other farm machinery.