Bead 4 : That part of a pneumatic tyre which fits and holds the tyre securely onto the wheel rim. It consists of a coil of high-tensile steel wire, treated to give good adhesion with rubber, and encased in a 'matrix' of hard rubber
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}