Audi R8 2017 Owner's Manual page 242

Wheels
Rim
means a metal s upport for a tire
or a tire and tube assembly upon
which the t ire beads are seated .
Rim diameter
means nomina l diameter of the
bead seat . If you change your
wh eel size, you will have to pur-
chase new tires to match the new
rim d iameter .
Rim size designation
means rim diameter and width.
Rim width
means nomina l distance between
rim flanges .
Sidewall
means that portion of a t ire be-
twee n the tread and bead .
Speed rating (letter code)
means the speed at which a t ire is
designed to be driven for extend-
ed periods of ti m e . The ratings
range from 93 mph (150 km/h)
to 186 mph (298 km/h)
¢
table
on page 236 .
You may not find
this information on all tires be-
cause it is not required by law.
The speed rating letter code,
wh ere applicable, is molded on
the t ire sidewall and ind icates the
2 4 0
maximum permissible road
speeds
¢
A
in Winter tires on
page 250 .
Tire pressure monitoring
system*
means a system that detects
when one or mo re of a vehicle's
tires are underinflated and illumi -
nates a low tire pressure war ning
telltale .
Tread
means that portion of a tire that
comes into contact wit h the road.
Tread separation
means pulling away of the tread
from the tire carcass .
Treadwear indicators (TWI)
means t he project ions wit hin t he
pr incipal grooves designed to give
a visua l indication of the degrees
of wear of the tread . See
¢
page 244, Treadwear indicator
for mo re information on meas ur-
ing tire wear.
Uniform Tire Quality Grading
is a tire informa t ion system devel -
oped by the Unite d States Nation -
al Highway Traffic Safety Admin-
istration (NHTSA) that is designed
to help buyers make re lative
..