Tire Balance And Wheel Alignment
To avoid vibration or shaking of the vehicle when a
tire rotates, the tire must be properly balanced. This
balance is achieved by positioning weights on the wheel
to counterbalance heavy spots on the wheel-and-tire
assembly. A wheel alignment adjusts the angles of the
wheels so that they are positioned correctly relative to
the vehicle's frame. This adjustment maximizes the life of
your tires. These adjustments require special equipment
and should be performed by a qualified technician.
Tire Repair
The proper repair of a punctured tire requires a plug
for the hole and a patch for the area inside the tire that
surrounds the puncture hole. Punctures through the tread
can be repaired if they are not too large, but punctures
to the sidewall should not be repaired. Tires must be
removed from the rim to be properly inspected before
being plugged and patched.
Tire Fundamentals
Federal law requires tire manufacturers to place
standardized information on the sidewall of all tires. This
information identifies and describes the fundamental
characteristics of the tire and also provides a tire
identification number for safety standard certification and
in case of a recall.
Information on Passenger Vehicle Tires
Please refer to Figure 24 and the information following.
24
B
C
D
A
K
J
A- 'P' indicates the tire is for passenger vehicles.
B- This three-digit number gives the width in millimeters
of the tire from sidewall edge to sidewall edge. In general,
the larger the number, the wider the tire.
E
F
G
H
I
C- This two-digit number, known as the aspect ratio, gives
the tire's ratio of height to width. Numbers of 70 or lower
indicate a short sidewall for improved steering response
and better overall handling on dry pavement.
D- "R" stands for radial. Radial ply construction of tires
has been the industry standard for the past 20 years.
E- This two-digit number is the wheel or rim diameter in
inches. If you change your wheel size, you will have to
purchase new tires to match the new wheel diameter.
F-
(Number) This two- or three-digit number is the tire's load
index. It is a measurement of how much weight each tire
can support. You may find this information in your owner's
manual. If not, contact a local tire dealer. Note: You may
not find this information on all tires because it is not
required by law.
(Letter) The speed rating denotes the speed at which a
tire is designed to be driven for extended periods of time.
The ratings range from 99 miles per hour (mph) to 186
mph. These ratings are listed below. Note: You may not
find this information on all tires because it is not required
by law.
Letter Rating
Q
R
S
T
U
H
V
Y
*Note: For tires with a maximum speed capability over
149 mph, tire manufacturers sometimes use the letters
ZR. For those with a maximum speed capability over 186
mph, tire manufacturers always use the letters ZR.
G- U.S. DOT Tire Identification Number. This begins with
the letters "DOT" and indicates that the tire meets all
federal standards. The next two numbers or letters are the
plant code where it was manufactured, and the last four
numbers represent the week and year the tire was built.
For example, the numbers 3197 means the 31st week of
1997. The other numbers are marketing codes used at
the manufacturer's discretion. This information is used to
contact consumers if a tire defect requires a recall.
H- The "M+S" or "M/S" indicates that the tire has some
mud and snow capability. Most radial tires have these
markings; hence, they have some mud and snow
capability.
I- Tire Ply Composition and Materials Used. The number
of plies indicates the number of layers of rubber-coated
fabric in the tire. In general, the greater the number
of plies, the more weight a tire can support. Tire
manufacturers also must indicate the materials in the tire,
which include steel, nylon, polyester, and others.
Speed Rating
99 mph
106 mph
112 mph
118 mph
124 mph
130 mph
168 mph*
186 mph*
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