A. No person shall operate a motor vehicle, trailer, or semitrailer on any highway in the Commonwealth if it is equipped with one or more tires which:
1. When measured in any two adjacent major tread grooves where the tread is thinnest, at three equally spaced intervals around the circumference of the tire and exclusive of “tiebars” by a tread depth gauge calibrated in thirty-seconds of an inch, are found to have tread depth of less than two thirty-seconds of an inch at such locations; or
2. When equipped with tread wear indicators, are found to have such indicators in contact with pavement at any two adjacent grooves at three equally spaced intervals around the circumference of the tire.
B. No motor vehicle, trailer, or semitrailer shall be issued a safety inspection approval sticker if equipped with any tire whose use is prohibited under the provisions of this section.
C. This section shall not apply to tires mounted on dual wheels installed on motor vehicles which have seats for more than seven passengers and are (i) operated wholly within a municipality, or (ii) operated by urban and suburban bus lines. For purposes of this section, “urban and suburban bus lines” are defined as bus lines operating over regular scheduled routes the majority of whose passengers use the buses for traveling one-way distances not exceeding forty miles on the same day between their residence and their place of work, shopping areas, or schools.
D. The foregoing exemptions shall not apply to buses owned or operated by any public school district, private school, or contract operator of school buses.
E. The provisions of this section shall not apply to any vehicle not required to be registered or licensed.