In general conformity with ASTM D4814 and the adoption of NIST Handbook 130, 2020, in rules promulgated pursuant to this chapter, the minimum (R+M)/2 octane rating grades of petroleum products, as defined by subdivision 37-2-5(10) in the counties of Butte, Custer, Fall River, Harding, Lawrence, Meade, Oglala Lakota, Pennington, and Perkins shall be no less than the following:
(1) Regular, unleaded, regular unleaded 85;
(2) Midgrade, plus, or super unleaded 87, 88, 89, or 90; and
(3) Premium, supreme, high test unleaded 91.