Tread Wear Indicator; Tire Terminology - Volvo S90 2019 Owner's Manual

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.
Related information
Tires (p. 500)
•

Tire terminology

The following is a glossary of tire-related
terms.
The tire suppliers may have additional mark-
ings, notes or warnings such as standard load,
radial tubeless, etc.
Tire information placard: A placard
•
showing the OE (Original Equipment) tire
sizes, recommended inflation pressure,
and the maximum weight the vehicle can
carry.
Tire Identification Number (TIN): A num-
•
ber on the sidewall of each tire providing
information about the tire brand and man-
ufacturing plant, tire size and date of man-
ufacture.
Inflation pressure: A measure of the
•
amount of air in a tire.
Standard load: A class of P-metric or
•
Metric tires designed to carry a maximum
load at 35 psi [37 psi (2.5 bar) for Metric
tires]. Increasing the inflation pressure
beyond this pressure will not increase the
tires load carrying capability.
Extra load: A class of P-metric or Metric
•
tires designed to carry a heavier maximum
load at 41 psi [43 psi (2.9 bar) for Metric
tires]. Increasing the inflation pressure
beyond this pressure will not increase the
tire's load carrying capability.
WHEELS AND TIRES
kPa: Kilopascal, a metric unit of air pres-
•
sure.
PSI: Pounds per square inch, a standard
•
unit of air pressure.
B-pillar: The structural member at the
•
side of the vehicle behind the front door.
Bead area of the tire: Area of the tire next
•
to the rim.
Sidewall of the tire: Area between the
•
bead area and the tread.
Tread area of the tire: Area of the perime-
•
ter of the tire that contacts the road when
mounted on the vehicle.
Rim: The metal support (wheel) for a tire
•
or a tire and tube assembly upon which
the tire beads are seated.
Maximum load rating: a figure indicating
•
the maximum load in pounds and kilo-
grams that can be carried by the tire. This
rating is established by the tire manufac-
turer.
Maximum permissible inflation
•
pressure: the greatest amount of air pres-
sure that should ever be put in the tire.
This limit is set by the tire manufacturer.
Recommended tire inflation pressure:
•
inflation pressure, established by Volvo,
which is based on the type of tires that are
mounted on a vehicle at the factory. This
information can be found on the tire infla-
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