The transportation commission may adopt rules setting the maximum speed at which it shall be lawful for any motor vehicle, trailer, or wagon to be driven upon the public highways of this state, the gross weight of which, including the load, is more than ten thousand pounds, or any motor vehicle, trailer, or wagon having gross weight more than eight thousand pounds on one axle, or any motor vehicle, trailer, or wagon having a gross load of over six hundred pounds per inch width of tire, upon any wheel concentrated upon the surface of the highway, said width in the case of rubber tires to be measured between the flanges of the rim. A violation of such rules is a Class 2 misdemeanor.
SDCL 32-25-6