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192
Tires and wheels
Tread
means that portion of a tire that comes into
contact with the road.
Tread separation
means pull ing away of the t read from the tire
carcass .
Treadwear indicators (TWI)
means the projections within the principal
grooves designed to give a visual ind ication of
the degrees of wear of the tread . See
~ page 198, Tread Wear Indicator (TWI)
for
more informat ion on measuring tire wear.
Uniform Tire Quality Grading
is a tire information system developed by the
United States National Highway Traffic Safety
Administration (NHTSA) that is designed to
help buyers make relative comparisons among
tires. The UTQG is not a safety rating and not a
guarantee that a t ire will last fo r a prescribed
number of mi les or perform in a certain way.
It simply gives tire buyers additional informa-
tion to combine with other considerations,
such as price, brand loyalty and dea ler recom-
mendations. Under UTQG, tires are graded by
the tire manufacturers
in three areas: tread-
wear, tract ion and temperature
resistance.
The UTQG information on the tires, molded in-
to the sidewalls .
U.S. DOT Tire Identification Number (TIN)
This is the tire's "serial number"
It
begins
with the letters "DOT" and indicates that the
tire meets a ll federal standards. The next two
numbers or letters indicate the plant where it
was manufactured,
and the last four numbers
represent the week and year of manufacture.
For example,
DOT ...
2210 ...
means that the tire was produced in the 22nd
week of 2010. The other numbers are market-
ing codes that may or may not be used by the
tire manufacturer . This information is used to
contact consumers if a tire defect requires a
recall.
Vehicle capacity weight
means the rated cargo and luggage load plus
150 lb s. (68 kilograms) times the vehicle's to-
ta l seating capacity as listed on the label lo-
cated on the driver's side B-pillar.
Vehicle maximum load on the tire
means that load on an individua l tire that is
determined by distributing to each axle its
share of the maximum loaded vehicle weight
and dividing by two.
Vehicle normal load on the tire
means that loa d on an individua l tire that is
determined by distributing to eac h axle its
share of the curb weight, accessory weight,
and normal occupant weight (distributed in
accordance with tab le below ~
page 192)
and dividing by two.
Occupant loading and distribution for vehicle normal load for various designated seating
capacities
I
Designated seating capacity,
Vehicle normal load,
number of occupants
number of occupants
2
2
Normally loaded vehicle,
occupant distribution
•
2 in front
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