Tread Wear Indicator (TWI)
Tread-wear indicators (TWI) means the projections
within the tread grooves designed to give a visual indication of the degree of wear of the tread.
Tyres with Non Skid Depth (N.S.D.)
less than 0.8mm for two and three wheeler tyres and 1.6 mm for other motor vehicles tyres are unsafe to drive. Tyres worn beyond these limits are not fit for use.
How to check if remaining tread depth is lower than the above limits:
- Every tyre has “TWI bars” in the main grooves and TWI indicators in the shoulder region on at least 6 locations around the circumference.
Different manufacturers use different marks / symbols to indicate TWI