Cap and Base : A pneumatic tyre tread formed from two separate strips of compound having different physical characteristics; the upper strip or cap forming tread pattern and the lower strip of base forming the undertread
Ministry of Business, Innovation and Employment, Glossary of terms and acronyms, Wellington, New Zealand 2010. http://wwwsosh.govt.nz/resources/glossary-u.shtml, (Occupn Hlth and Sfty - Brit) {530}