TWI
Definition
Treadwear indicator. A small raised ridge moulded across the tread groove of every tire at 1.6 mm depth. When the surrounding tread wears down to the TWI, the tire is bald. The 1.6 mm minimum is mandated in India by CMVR Rule 94.
- Full term
- Treadwear indicator
- Trigger depth
- 1.6 mm
- Location
- Raised ridge across the tread groove
- India regulation
- CMVR Rule 94 mandates the 1.6 mm minimum
Common questions
How does a TWI help an investigator examining a tire impression at a scene?+
Once tread has worn down to the TWI, the tire is legally bald and its impression will lack distinguishing tread pattern detail, so an examiner comparing a scene impression against a suspect vehicle's tire needs to account for wear state affecting how much individualising detail is available.
Does TWI placement vary between tire manufacturers or models?+
The 1.6 mm trigger depth is the common regulatory minimum in most jurisdictions, but the number and exact placement of TWI markers around the tire's circumference is set by the manufacturer and can differ between models.
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