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.)
The steering wheel paddles are a supplement to the gear selector and make
it possible to shift manually without removing your hands from the steering wheel.
The function is available in position D or M.
"-": Shift down one gear...
Kickdown can be used when maximum acceleration is needed e.g. when passing.
When the accelerator pedal is depressed all the way to the floor (past the normal
full accelerator position), the transmission will automatically engage kickdown,
i.e. immediately shift down to a lower gear...