GMC 2012 Savana Owner's Manual page 312

We recommend that the tires,
including the spare tire, if the
vehicle has one, be inspected
for signs of wear or damage at
least once a month.
Replace the tire if:
The indicators at three or
more places around the tire
can be seen.
There is cord or fabric
showing through the tire's
rubber.
The tread or sidewall is
cracked, cut, or snagged
deep enough to show cord or
fabric.
The tire has a bump, bulge,
or split.
The tire has a puncture, cut,
or other damage that cannot
be repaired well because of
the size or location of the
damage.
Tires should be rotated every
12 000 km (7,500 mi). See
.
Tires are rotated to achieve a
uniform wear for all tires. The
first rotation is the most
important.
Any time unusual wear is
noticed, rotate the tires as
soon as possible and check the
wheel alignment. Also check for
damaged tires or wheels. See
and
Use this rotation pattern when
rotating the tires.
If the vehicle has a compact
spare tire, do not include it in the
tire rotation.
Adjust the front and rear tires
to the recommended inflation
pressure on the Tire and
Loading Information label after
the tires have been rotated. See
.
and
.