[Excaliber]

Regarding motorcycle helmets: As I understand it the difference between a motorcycle helmet and an auto helmet, when both have a current race approved rating, is the fire retardant rating of each. The auto helmet is fire rated, the motorcycle helmet is not. However, the motorcycle fire retardant rating is the same for the motorcycle IF you wear an approved head sock under the helmet!

Some clubs accept this standard and allow motorcycle helmets. I actually have both, a motorcycle helmet with head sock and approved rating and a Bell auto racing helmet. I am allowed to use either one here at my local track, the motorcycle helmet in case a passenger may need it, or just a spare.