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When It Is Time for New
Tires
Factors such as maintenance,
temperatures, driving speeds,
vehicle loading, and road conditions
affect the wear rate of the tires.
Treadwear indicators are one way to
tell when it is time for new tires.
Treadwear indicators appear when
the tires have only 1.6 mm (1/16 in)
or less of tread remaining.
Some commercial truck tires,
including Goodyear LT225/75R16
G949 RSA and Goodyear LT225/
75R16 G933 RSD, may not have
treadwear indicators. If the tires do
not have treadwear indicators,
replace the tires when the tread
depth is down to 3.2 mm (1/8 in) for
the front tires, or 1.6 mm (1/16 in) for
the rear tires. See Tire Inspection
on page 10-61 and Tire Rotation on
page 10-61 for additional
information.
The rubber in tires ages over time.
This also applies to the spare tire,
if the vehicle has one, even if it is
never used. Multiple factors
including temperatures, loading
conditions, and inflation pressure
maintenance affect how fast aging
takes place. GM recommends that
tires, including the spare if
equipped, be replaced after six
years, regardless of tread wear. The
tire manufacturer date is the last
four digits of the DOT Tire
Identification Number (TIN) which is
molded into one side of the tire
Vehicle Care
sidewall. The first two digits
represent the week (01-52) and the
last two digits, the year. For
example, the third week of the year
2010 would have a four-digit DOT
date of 0310.
Vehicle Storage
Tires age when stored normally
mounted on a parked vehicle. Park
a vehicle that will be stored for at
least a month in a cool, dry, clean
area away from direct sunlight to
slow aging. This area should be free
of grease, gasoline or other
substances that can deteriorate
rubber.
Parking for an extended period can
cause flat spots on the tires that
may result in vibrations while
driving. When storing a vehicle for
at least a month, remove the tires or
raise the vehicle to reduce the
weight from the tires.
10-63
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