Volvo XC90: Wheels and tires / Tread wear indicator
The tread wear indicator shows the status of the tire's tread.

The tread wear indicator is a narrow elevated strip running across the tire's
longitudinal tread grooves. The letters TWI (Tread Wear Indicator) are visible on
the side of the tire. When approximately 1.6 mm (1/16 inch) is left on the tread,
the tread will be at the same height as the tread wear indicator. Replace the tire
as soon as possible. Tires with low tread offer very poor traction in rain or snow.
Tires with tread designed to roll in only one direction are marked with an
arrow on the sidewall.
The arrow shows the tire's direction of rotation.
The tire should maintain the same direction of rotation throughout its service
life...
The following is a glossary of tire-related terms.
The tire suppliers may have additional markings, notes or warnings such as standard
load, radial tubeless, etc...
Other information:
The vehicle's trip computer registers data while driving such as mileage,
fuel consumption and average speed.
To help promote fuel-efficient driving, data is recorded on both current and
average fuel consumption. Data from the trip computer can be displayed in the instrument
panel...
Messages saved from the instrument panel and center displays are handled in
the center display.
Examples of saved messages and possible selections in Top view.
Messages that have been shown in the center display and that need to be saved
are stored in the center display's Top view...