Tread Wear Indicators : Various devices incorporated in the base of the tread pattern of a tyre, usually in the form of small raised platforms spaced at intervals around the base of the circumferential grooves of the pattern
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}