What are Tread Wear Indicators (TWIs)?
Tread Wear Indicators (TWIs) are designed to let you know when your tires are beginning to wear down and need to be replaced. These indicators are usually located in the tread grooves of the tire, and they can be either raised or recessed. When the tread depth reaches the level of the indicator, it’s time for new tires.
Most passenger car and light truck tires have tread wear indicators into the tread design. The depth of the tread grooves on these tires typically starts at about 10/32 inch (8 millimeters). When the tire is new, the tread wear indicator is flush with the rest of the tread. As the tire wears down, the indicator becomes more visible.
Not all tires have tread wear indicators. Some truck tires and winter tires, for example, don’t have them. If you’re not sure whether your tires have tread wear indicators, check the owner’s manual or ask a tire professional.