Volkswagen Golf 2021 Owner's Manual page 295

sures than the corresponding stand-
ard tire.
Rim
The outer edge of a wheel upon
which the tire beads are seated.
Rim diameter
The nominal diameter of the wheel's
tire bead seating surface. If you
change your wheel size, to wheels of
a different diameter, you will have to
purchase new tires to match the
new wheels.
Rim size
Designation means rim diameter and
width.
Rim type designation
The industry or manufacturer's des-
ignation for a rim by style or code.
Rim width
The nominal distance between
wheel rim flanges.
Section width
The linear distance between the ex-
teriors of the sidewalls of an inflated
tire, excluding elevations due to la-
beling decoration, or protective
bands.
Sidewall
The portion of a tire between the
bead and the tread.
Sidewall separation
The parting of the rubber compound
from the cord material in the side-
wall.
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Important information on tires and wheels
Speed rating (letter code)
A standardized letter code indicating
the maximum speed at which a tire
is designed to be driven for extend-
ed periods of time. The ratings range
from 93 mph (150 km/h) "P" to
186 mph (300 km/h) "Y".
The speed rating letter code, where
applicable, is molded on the tire
sidewall → page 284, Tire labeling.
You may not find this information on
all tires because it is not required by
law.
Tire Pressure Monitoring System
A system that detects when at least
one of a vehicle's tires is underinflat-
ed and illuminates a low tire-pres-
sure warning light.
Tread
The portion of a tire that normally
touches the road.
Tread rib
A tread section running circumferen-
tially around a tire.
Tread separation
Tire failure caused by the tread pull-
ing away from the tire carcass.
Tread wear indicators (TWI)
Raised areas within the main tread
grooves that show, visually, when
tires are worn and near the end of
their useful life → page 279, Tread
depth and tread wear indicators.
Uniform Tire Quality Grading (UTQG)
A tire information system developed
by the U.S. National Highway Traffic
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