Pontiac Fiero 1988 Service Manual page 205

3E-2 TIRES AND WHEELS
THE TYPE
3 - PASSENGER
r TEMPORARY
I COMMERCIAL
METRIC T l i E SUES
/ §§ I
A S P E C T ^ R / I T O
(SECTION HEIGHT)
(SECTION WIDTH)
SECTION WIDTH
(MILLIMETERS)
185
195
205
ETC
70
75
80
mm DIAMETER
(INCHES)
13
14
15
CONSTRUCTION TYPE
R - RADIAL
8 • BIAS - BELTED
D DIAGONAL (BIAS)
G33952-3E-AN
Fig. 2 Metric Tire Size Format
tires qualify as snow tires, with a 37% higher average
rating for snow traction than the non-All Seasons
radial tires previously used. Other performance areas,
such as wet traction, rolling resistance, tread life, and
air retention, were also improved slightly. This was
done by improvements in both tread design and tread
compounds. These tires are identified by an "M + S"
molding in the tire sidewall following the size. The
suffix "MS" is also molded in the sidewall after the
TPC specification number.
The optional handling tires used on some cars are
not All Seasons tires. These will not have the "MS"
marking after the tire size or TPC specification
number.
P-METRIC SIZED T I R E S
Figs. 1 through 4
All GM cars now use P-metric sized tires.
P-metric tires are available in two load ranges,
standard load (35 psi max) and extra load (41 psi max).
Most passenger car tires are standard load.
Most P-metric tire sizes do not have exact
corresponding alpha-numeric tire sizes. For example,
a P205/75R15 is not exactly equal in size and load
carrying capacity to an FR78-15. For this reason,
replacement tires should be of the same TPC
specification number (same size, load range,
construction) as those originally on the car. If P-metric
tires must be replaced with other sizes, a tire dealer
should be consulted. Tire companies can best
recommend the closest match of alpha-numeric to
P-metric sizes within their own tire lines.
The metric term for tire inflation pressure is the
kilopascal (kPa). Tire pressure may be printed in both
kPa and psi. One psi equals 6.9 kPa.
See the tire placard or Section OB for tire inflation
specifications.
TIRE PLACARD
Fig. 4
The tire placard is permanently located on the
rear face of the driver's door, and should be referred
to for tire information. The placard lists the maximum
car load, tire size (including spare), and cold inflation
pressure (including spare).
WHEELS
Wheels must be replaced if they are bent, dented,
have excessive lateral or radial runout, leak air through
welds, have elongated bolt holes, if wheel nuts won't
stay tight, or if they are heavily rusted. Wheels with
excessive runout may cause objectional vibrations.
Replacement wheels must be equivalent to the
original equipment wheels in load capacity, diameter,
rim width, offset, and mounting configuration. A
wheel of improper size or type may affect wheel and
bearing life, brake cooling, speedometer/odometer
calibration, car ground clearance, and tire clearance to
the body and chassis.
Steel wheels can be identified by a two or
three-letter code stamped into the rim near the valve
INFLATION PRESSURE CONVERSION C H A R T
(KILOPASCALS TO PSI)
kPa
J2§L
kPa psi
140 20
215 31
145 21 220
32
155
22 230 33
160 23
235 34
165
24 240 35
170 25 250
36
180
26 275 40
185
27 310 45
190 28 345 50
200 29 380 55
205
30 415 60
Conversion: 6.9 kPa = 1 psi
_ _ _ G33987-3E-AN
Fig. 3 Inflation Pressure Conversion
stem. Aluminum wheels have the code, part number,
and manufacturer ID cast into their back side.
MAINTENANCE AND ADJUSTMENTS
W H E E L R E P A I R
Wheel repairs that use welding, heating, or
peening are not approved. An inner tube is not an
acceptable repair for leaky wheels or tires. Porosity in
aluminum wheels can be repaired, see Aluminum
Wheel Porosity Repair.