749
Maintenance
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4.Tire ply composition and mate-
rial
The number of layers or plies of rub-
bercoated fabric in the tire. Tire man-
ufacturers also must indicate the
materials in the tire, which include
steel, nylon, polyester, and others.
The letter "R" means radial ply con-
struction; the letter "D" means diago-
nal or bias ply construction; and the
letter "B" means belted-bias ply con-
struction.
5. Maximum permissible inflation
pressure
This number is the greatest amount
of air pressure that should be put in
the tire. Do not exceed the maximum
permissible inflation pressure. Refer
to the Tire and Loading Information
label for recommended inflation
pressure.
6. Maximum load rating
This number indicates the maximum
load in kilograms and pounds that
can be carried by the tire. When
replacing the tires on the vehicle,
always use a tire that has the same
load rating as the factory installed
tire.
7. Uniform tire quality grading
The following information relates to
the tire grading system developed by
the National Highway Traffic Safety
Administration (NHTSA) for grading
tires by tread wear, traction and tem-
perature performance.
WARNING - Tire age
Tires degrade over time, even
when they are not being used.
Regardless of the remaining
tread, it is recommended that
tires generally be replaced after
six (6) years of normal service.
Heat caused by hot climates or
frequent high loading condi-
tions can accelerate the aging
process. Failure to follow this
warning can result in sudden
tire failure, which could lead to a
loss of control and an accident
involving serious injury or
death.
