All state agencies, departments, and authorities shall replace original truck tires of over 16 inch rim size used on nonsteering axles with retreaded tires or subscribe to a retread service as replacement is necessary and as stockpiled tires are depleted; provided, however, that nothing in this Code section shall be construed so as to discourage the use of retreaded tires on other size rims or other types of vehicles if an agency, department, or authority deems such use to be economical, feasible, and desirable.