Traction assist devices

(a) Each school bus shall carry a full set of tire chains or other traction assist devices approved by the commissioner for installation on at least one (1) rear tire on each side of the bus whenever weather or highway conditions require such use. (b) In lieu of the traction assist devices of subsection (a) of this section, each school bus may use tires designed to prevent skidding on all drive wheels, provided such tires have a minimum tread depth of at least four thirty-seconds (4/32) of an inch. Tires designed to prevent skidding shall comply with the requirements of subsection (c). (c) A tire designed to prevent skidding means: 1. Any studded snow tire with a minimum of six (6) studs per fifty (50) square inches of tread surface; 2. Any snow tire that has microsipes, as hereinafter defined, to a minimum depth of four thirty seconds (4/32) of an inch; 3. Any snow tire having an aggressive tread design providing equivalent stopping traction on ice and starting traction on medium pack snow to that of a tire meeting the standards of subdivision (2) of this subsection and included on a list maintained by the Commissioner of Motor Vehicles and made available upon request; or 4. Any tire equivalent in traction to tires meeting the requirements of subdivision 1, 2 or 3 as certified under penalty of false statement by the superintendent of schools or other person responsible for school transportation. Such certification shall be on file at the location where such school buses are normally inspected by an Inspector of the Department of Motor Vehicles, and shall be made available at the request of the commissioner. (d) A microsipe means a cut entirely across the outside of the tread of a tire at intervals of not less than three-eighths (3/8) of an inch and not more than one (1) inch apart around the entire circumference of such tire.