Page 334 of 432

Black plate (58,1)Chevrolet Corvette Owner Manual - 2012
10-58 Vehicle Care
Tire Sidewall Labeling
Useful information about a tire
is molded into its sidewall.
The examples show a typical
passenger tire sidewall.
Passenger (P‐Metric) Tire Example
(A) Tire Size:The tire size is
a combination of letters and
numbers used to define a
particular tire's width, height,
aspect ratio, construction type,
and service description. See the
“Tire Size” illustration later in this
section for more detail. (B) TPC Spec (Tire
Performance Criteria
Specification)
:Original
equipment tires designed to
GM's specific tire performance
criteria have a TPC specification
code molded onto the sidewall.
GM's TPC specifications meet
or exceed all federal safety
guidelines.
(C) DOT (Department of
Transportation)
:The
Department of Transportation
(DOT) code indicates that
the tire is in compliance with
the U.S. Department of
Transportation Motor Vehicle
Safety Standards.
(D) Tire Identification Number
(TIN)
:The letters and numbers
following the DOT code are
the Tire Identification Number
(TIN). The TIN shows the
manufacturer and plant code, tire size, and date the tire was
manufactured. The TIN is
molded onto both sides of the
tire, although only one side may
have the date of manufacture.
(E) Tire Ply Material
:The type
of cord and number of plies in
the sidewall and under the tread.
(F) Uniform Tire Quality
Grading (UTQG)
:Tire
manufacturers are required to
grade tires based on three
performance factors: treadwear,
traction, and temperature
resistance. For more information
see Uniform Tire Quality
Grading on page 10‑72.
(G) Maximum Cold Inflation
Load Limit
:Maximum load
that can be carried and the
maximum pressure needed to
support that load.
Page 335 of 432

Black plate (59,1)Chevrolet Corvette Owner Manual - 2012
Vehicle Care 10-59
Tire Designations
Tire Size
The following is an example
of a typical passenger vehicle
tire size.
(A) Passenger (P‐Metric) Tire:
The United States version
of a metric tire sizing system.
The letter P as the first
character in the tire size
means a passenger vehicle
tire engineered to standards
set by the U.S. Tire and Rim
Association.
(B) Tire Width
:The three‐digit
number indicates the tire
section width in millimeters
from sidewall to sidewall. (C) Aspect Ratio
:A two‐digit
number that indicates the tire
height‐to‐width measurements.
For example, if the tire size
aspect ratio is 60, as shown in
item C of the illustration, it would
mean that the tire's sidewall is
60 percent as high as it is wide.
(D) Construction Code
:
A letter code is used to indicate
the type of ply construction in
the tire. The letter R means
radial ply construction; the
letter D means diagonal or
bias ply construction; and the
letter B means belted‐bias ply
construction.
(E) Rim Diameter
:Diameter of
the wheel in inches.
(F) Service Description
:
These characters represent
the load index and speed rating
of the tire. The load index
represents the load carrying capacity a tire is certified to
carry. The speed rating is the
maximum speed a tire is
certified to carry a load.
Tire Terminology and
Definitions
Air Pressure:The amount of
air inside the tire pressing
outward on each square inch
of the tire. Air pressure is
expressed in kPa (kilopascal)
or psi (pounds per square inch).
Accessory Weight
:The
combined weight of optional
accessories. Some examples of
optional accessories are
automatic transmission, power
steering, power brakes, power
windows, power seats, and air
conditioning.
Aspect Ratio
:The relationship
of a tire's height to its width.
Page 348 of 432

Black plate (72,1)Chevrolet Corvette Owner Manual - 2012
10-72 Vehicle Care
Different Size Tires and
Wheels
If wheels or tires are installed that
are a different size than the original
equipment wheels and tires, vehicle
performance, including its braking,
ride and handling characteristics,
stability, and resistance to rollover
may be affected. If the vehicle has
electronic systems such as antilock
brakes, rollover airbags, traction
control, and electronic stability
control, the performance of these
systems can also be affected.
{WARNING
If different sized wheels are used,
there may not be an acceptable
level of performance and safety
if tires not recommended for
those wheels are selected.
This increases the chance of a
crash and serious injury. Only use
GM specific wheel and tire
systems developed for the
vehicle, and have them properly
installed by a GM certified
technician.
See Buying New Tires on
page 10‑70 andAccessories and
Modifications on page 10‑3 for
additional information.
Uniform Tire Quality
Grading
Quality grades can be found
where applicable on the tire
sidewall between tread shoulder
and maximum section width.
For example:
Treadwear 200 Traction AA
Temperature A
The following information relates
to the system developed by the
United States National Highway
Traffic Safety Administration
(NHTSA), which grades tires
by treadwear, traction, and
temperature performance.
This applies only to vehicles
sold in the United States.
Page 351 of 432

Black plate (75,1)Chevrolet Corvette Owner Manual - 2012
Vehicle Care 10-75
Each new wheel should have the
same load-carrying capacity,
diameter, width, offset, and be
mounted the same way as the one
it replaces.
Replace wheels, wheel bolts,
or wheel nuts with new GM original
equipment parts.
{WARNING
Using the wrong replacement
wheels, wheel bolts, or wheel
nuts can be dangerous. It could
affect the braking and handling of
the vehicle. Tires can lose air,
and cause loss of control, causing
a crash. Always use the correct
wheel, wheel bolts, and wheel
nuts for replacement.
{WARNING
Replacing a wheel with a used
one is dangerous. How it has
been used or how far it has been
driven may be unknown. It could
fail suddenly and cause a crash.
When replacing wheels, use a
new GM original equipment
wheel.
Notice: The wrong wheel can
also cause problems with
bearing life, brake cooling,
speedometer or odometer
calibration, headlamp aim,
bumper height, vehicle ground
clearance, and tire clearance to
the body and chassis.
{WARNING
Rust or dirt on a wheel,
or on the parts to which it is
fastened, can make wheel
nuts become loose after a
time. The wheel could come
off and cause a crash.
When changing a wheel,
remove any rust or dirt from
places where the wheel
attaches to the vehicle. In an
emergency, a cloth or a paper
towel can be used, however,
use a scraper or wire brush to
remove all rust or dirt.