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:
(Option/accessory.)
(Depending on market, this function can be either standard or optional.)
Pilot Assist can be deactivated and put in standby mode. This may happen automatically
or be due to driver intervention.
Standby mode means that the function is selected in the instrument panel but
not activated...
Regularly check the brake system components for wear.
To keep the vehicle as safe and reliable as possible, follow the Volvo service
schedule specified in the Warranty and Maintenance Records Information booklet.
After replacing brake pads and brake discs, braking effect is not adapted until
they are "broken in" by driving a few hundred kilometers (miles)...