For the purpose of this regulation, "snow tires" are
defined as those tires having antiskid patterns impressed or cut into
the treaded surfaces to form bars, buttons or blocks, or which contain
perforations, ingredients or metallic elements designated to give
effective traction on snow, mud or ice. Worn or damaged tires which
no longer provide effective traction shall not constitute snow tires
within the meaning of this section regardless of their original classification
or designation.