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:
Tire pressure decreases over time, which is normal. The tire pressure must
therefore be adjusted to maintain the recommended tire pressure.
Use the recommended inflation pressure for cold tires to help maintain good tire
performance and even wear.
NOTE
To help prevent incorrect inflation pressure, pressure should be checked when
the tires are cold...
Changing system units of measurement
Unit settings are adjusted in the Settings menu in the center display.
Tap Settings in the Top view in the center display.
Proceed to System System
Languages and Units Units of Measurement.
Choose a measurement standard:
Metric - kilometers, liters and degrees Celsius...