The narrow grooves that run lengthwise across the tire's tread pattern are tread wear indicators. On the side of the tire are the letters TWI1.
Important
- Tires should be changed before wearing them down to the tread wear indicators to avoid poor traction in rain and snow.
- Volvo recommends that winter tires have a greater tread depth than 3 millimeters (1/8 inch) and summer tires 1.6 millimeters (1/16 inch).