1975 NASCAR International Stock Car Racing Rule Book NASCAR Grand National ® Championship Division Section 20-31 -- Helmets

a. It is recommended that helmets meet the specifications set forth in Title 49, Code of Federal Regulations, Part 571, Federal Motor Vehicle Safety Standard Number 571.218 or meet the specifications set forth by the American National Standards Institute, Inc., in ANSI Z90.1 a 1971 and ANSI Z90.1 a 1973.