2014 SUBARU BRZ Owners Manual

433
6-1. Specifications
6
Vehicle specifications
■Treadwear
The treadwear grade is a comparative rating based on the wear
rate of the tire when tested under controlled conditions on a speci-
fied government test course.For example, a tire graded 150 would wear one and a half (1 - 1/2)
times as well on the government course as a tire graded 100.
The relative performance of tires depends upon the actual conditions
of their use. Performance may differ significantly from the norm due
to variations in driving habits, service practices and differences in
road characteristics and climate.
■Traction AA, A, B, C
The traction grades, from highest to lowest, are AA, A, B and C,
and they represent the tire’s ability to stop on wet pavement as
measured under controlled conditions on specified government
test surfaces of asphalt and concrete.
A tire marked C may have poor traction performance.
Warning: The traction grade assigned to this tire is based on braking
(straight ahead) traction tests and does not include cornering (turn-
ing) traction.
■Temperature A, B, C
The temperature grades are A (the highest), B, and C, represent-
ing the tire’s resistance to the generation of heat and its ability to
dissipate heat when tested under controlled conditions on a speci-
fied indoor laboratory test wheel.Sustained high temperature can cause the material of the tire to
degenerate and reduce tire life, and excessive temperature can lead
to sudden tire failure.
Grade C corresponds to a level of performance which all passenger
car tires must meet under the Federal Motor Vehicle Safety Standard
No. 109.
Grades B and A represent higher levels of performance on the labo-
ratory test wheel than the minimum required by law.

434
6-1. Specifications
Warning: The temperature grades of a tire assume that it is properly
inflated and not overloaded.
Excessive speed, underinflation, or excessive loading, either sepa-
rately or in combination, can cause heat buildup and possible tire fail-
ure.
Glossary of tire terminology
Tire related termMeaning
Cold tire inflation
pressure Tire pressure when the vehicle has been
parked for three hours or more, or has not
been driven more than 1 mile or 1.5 km under
that condition
Maximum inflation
pressure The maximum cold inflated pressure to which a
tire may be inflated, shown on the sidewall of
the tire
Recommended
inflation pressure Cold tire inflation pressure recommended by a
manufacturer.
Accessory weight The combined weight (in excess of those stan-
dard items which may be replaced) of auto-
matic transmission, power steering, power
brakes, power windows, power seats, radio
and heater, to the extent that these items are
available as factory-installed equipment
(whether installed or not)
Curb weight The weight of a motor vehicle with standard
equipment, including the maximum capacity of
fuel, oil and coolant, and if so equipped, air
conditioning and additional weight optional
engine
Maximum loaded
vehicle weight The sum of:
(a) Curb weight
(b) Accessory weight
(c) Vehicle capacity weight
(d) Production options weight

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6-1. Specifications
6
Vehicle specifications
Tire related termMeaning
Normal occupant
weight 150 lb. (68 kg) times the number of occupants
specified in the second column of Table 1
* that
follows
Occupant distribution Distribution of occupants in a vehicle as speci-
fied in the third column of Table 1
* below
Production options
weight The combined weight of installed regular pro-
duction options weighing over 5 lb. (2.3 kg) in
excess of the standard items which they
replace, not previously considered in curb
weight or accessory weight, including heavy
duty brakes, ride levelers, roof rack, heavy duty
battery, and special trim
Rim A metal support for a tire or a tire and tube
assembly upon which the tire beads are seated
Rim diameter
(Wheel diameter) Nominal diameter of the bead seat
Rim size designation Rim diameter and width
Rim type designation The industry manufacturer’s designation for a
rim by style or code
Rim width Nominal distance between rim flanges
Vehicle capacity
weight (Total load
capacity) The rated cargo and luggage load plus 150 lb.
(68 kg) times the vehicle’s designated seating
capacity
Vehicle maximum load
on the tire The load on an individual tire that is determined
by distributing to each axle its share of the
maximum loaded vehicle weight, and dividing
by two

436
6-1. Specifications
Tire related termMeaning
Vehicle normal load
on the tire The load on an individual tire that is determined
by distributing to each axle its share of curb
weight, accessory weight, and normal occu-
pant weight (distributed in accordance with
Table 1
* below), and dividing by two
Weather side The surface area of the rim not covered by the
inflated tire
Bead The part of the tire that is made of steel wires,
wrapped or reinforced by ply cords and that is
shaped to fit the rim
Bead separation A breakdown of the bond between components
in the bead
Bias ply tire A pneumatic tire in which the ply cords that
extend to the beads are laid at alternate angles
substantially less than 90 degrees to the cen-
terline of the tread
Carcass The tire structure, except tread and sidewall
rubber which, when inflated, bears the load
Chunking The breaking away of pieces of the tread or
sidewall
Cord The strands forming the plies in the tire
Cord separation The parting of cords from adjacent rubber com-
pounds
Cracking Any parting within the tread, sidewall, or inner-
liner of the tire extending to cord material
CT A pneumatic tire with an inverted flange tire
and rim system in which the rim is designed
with rim flanges pointed radially inward and the
tire is designed to fit on the underside of the
rim in a manner that encloses the rim flanges
inside the air cavity of the tire

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6-1. Specifications
6
Vehicle specifications
Tire related termMeaning
Extra load tire A tire designed to operate at higher loads and
at higher inflation pressures than the corre-
sponding standard tire
Groove The space between two adjacent tread ribs
Innerliner The layer(s) forming the inside surface of a
tubeless tire that contains the inflating medium
within the tire
Innerliner separation The parting of the innerliner from cord material
in the carcass
Intended outboard
sidewall (a)The sidewall that contains a whitewall, bears
white lettering, or bears manufacturer, brand,
and/or model name molding that is higher or
deeper than the same molding on the other
sidewall of the tire, or
(b)The outward facing sidewall of an asymmet-
rical tire that has a particular side that must
always face outward when mounted on a vehi-
cle
Light truck (LT) tire A tire designated by its manufacturer as prima-
rily intended for use on lightweight trucks or
multipurpose passenger vehicles
Load rating The maximum load that a tire is rated to carry
for a given inflation pressure
Maximum load rating The load rating for a tire at the maximum per-
missible inflation pressure for that tire
Maximum permissible
inflation pressure The maximum cold inflation pressure to which
a tire may be inflated
Measuring rim The rim on which a tire is fitted for physical
dimension requirements
Open splice Any parting at any junction of tread, sidewall, or
innerliner that extends to cord material
Outer diameter The overall diameter of an inflated new tire

438
6-1. Specifications
Tire related termMeaning
Overall width The linear distance between the exteriors of
the sidewalls of an inflated tire, including eleva-
tions due to labeling, decorations, or protective
bands or ribs
Passenger car tire A tire intended for use on passenger cars, mul-
tipurpose passenger vehicles, and trucks, that
have a gross vehicle weight rating (GVWR) of
10,000 lb. or less.
Ply A layer of rubber-coated parallel cords
Ply separation A parting of rubber compound between adja-
cent plies
Pneumatic tire A mechanical device made of rubber, chemi-
cals, fabric and steel or other materials, that,
when mounted on an automotive wheel, pro-
vides the traction and contains the gas or fluid
that sustains the load
Radial ply tire A pneumatic tire in which the ply cords that
extend to the beads are laid at substantially 90
degrees to the centerline of the tread
Reinforced tire A tire designed to operate at higher loads and
at higher inflation pressures than the corre-
sponding standard tire
Section width The linear distance between the exteriors of
the sidewalls of an inflated tire, excluding ele-
vations due to labeling, decoration, or protec-
tive bands
Sidewall That portion of a tire between the tread and bead
Sidewall separation The parting of the rubber compound from the
cord material in the sidewall

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6-1. Specifications
6
Vehicle specifications
*:Table 1  Occupant loading and distribution for vehicle normal load
for various designated seating capacities
Tire related termMeaning
Snow tire A tire that attains a traction index equal to or
greater than 110, compared to the ASTM E-
1136 Standard Reference Test Tire, when
using the snow traction test as described in
ASTM F-1805-00, Standard Test Method for
Single Wheel Driving Traction in a Straight Line
on Snow-and Ice-Covered Surfaces, and which
is marked with an Alpine Symbol ( ) on at
least one sidewall
Te s t r i m The rim on which a tire is fitted for testing, and
may be any rim listed as appropriate for use
with that tire
Tread That portion of a tire that comes into contact
with the road
Tread rib A tread section running circumferentially
around a tire
Tread separation Pulling away of the tread from the tire carcass
Treadwear indicators
(TWI) The projections within the principal grooves
designed to give a visual indication of the
degrees of wear of the tread
Wheel-holding fixture The fixture used to hold the wheel and tire
assembly securely during testing

440
6-1. Specifications
Designated seating
capacity, Number of occupantsVehicle normal load,
Number of occupantsOccupant distribution in a normally loaded vehicle
2 through 4 2 2 in front
5 through 10 3 2 in front, 1 in second
seat
11 through 15 5 2 in front, 1 in second
seat, 1 in third seat, 1
in fourth seat
16 through 20 7 2 in front, 2 in second
seat, 2 in third seat, 1
in fourth seat