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A small triangle or letters on the shoulder, pointing at a moulded wear bar.
Also known as: TWI mark, Wear bar indicator, Tread depth marker
A tread wear indicator is a small triangle, or the letters TWI, moulded onto a tyre's shoulder. It marks the position of a raised bar sunk in the bottom of the tread groove at the legal minimum depth. When the surface of the tread wears down level with that bar, the tyre is at the limit. The mark exists so that a driver can check by looking rather than by measuring, and the triangle is there to say where in the circumference to look.
Points at a raised bar moulded into the bottom of a tread groove at the legal minimum depth, so a tyre level with that bar is at the limit.
Contexts: Road signage, Vehicle dashboard
Turns a measurement into a look. The triangle exists to say where around the circumference the bars are, which is the part a driver checking a tyre by eye needs and would otherwise have to search for.
Contexts: Road signage, Vehicle dashboard
A small solid triangle pointing towards the tread, or three capital letters, moulded into the shoulder of a tyre.
Both are condition markings moulded into the same tyre.