TWI - is the abbreviation of 'Tread Wear Indicator' and may be found in the shoulder or upper sidewall part of some tyres
This marking is placed on the tyre to indicate where the tread wear indicators are located across the tread pattern. When these special markers in the tread pattern become flush with the remainder of the tread, it indicates the tyre is or is about to become illegal, because of lack of tread depth.
