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.)
Here are some useful tips for when you use Android Auto1.
Ensure that your apps are updated.
When starting the vehicle, wait until the center display has started, connect
the device and then open Android Auto from the app view...
(Option/accessory.)
There is a function button for driving at low speeds with Hill Descent
Control in the center display's Function view if the vehicle is not equipped
with a drive mode control in the tunnel console.
Selecting Low Speed Control in the center display's Function view
Tap the Hill Descent Control button to activate or deactivate the
function...