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.

Source: SL 2013, ch 187, § 6, eff. Mar. 6, 2013; SL 2015, ch 56 (HJR 1005), eff. May 1, 2015; SL 2016, ch 183, § 15; SL 2020, ch 170, § 7.