RCW 46.61.455: Vehicles with solid or hollow cushion tires.

Except for vehicles equipped with temporary-use spare tires that meet federal standards, it shall be unlawful to operate any vehicle equipped or partly equipped with solid rubber tires or hollow center cushion tires, or to operate any combination of vehicles any part of which is equipped or partly equipped with solid rubber tires or hollow center cushion tires, so long as solid rubber tires or hollow center cushion tires may be used under the provisions of this title, upon any public highway of this state at a greater rate of speed than ten miles per hour: PROVIDED, That the temporary-use spare tires are installed and used in accordance with the manufacturer's instructions.