S.D. Codified Laws § 32-20-4.2
Protective devices not required of riders in enclosed cab
Section 32-20-4 , requiring helmets, and § 32-20-4.1 shall not apply to persons riding within an enclosed cab.
Source: SL 1970, ch 176, § 3.
S.D. Codified Laws § 32-20-4.2