Non-Directional Tread : A general-purpose tread pattern designed so that the tyre can be run in either direction without loss of traction or self-cleaning properties
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}