GMC 2007 Sierra - Manual (Page 547)

(F) Tire Ply Material: The type of cord and
number of plies in the sidewall and under
the tread.
(G) Single Tire Maximum Load: Maximum load
that can be carried and the maximum pressure
needed to support that load when used as a
single. For information on recommended
tire pressure see Inflation - Tire Pressure on
page 551 and Loading Your Vehicle on page 409.
Tire Size
The following examples show the different parts of
a tire size.
(A) Passenger (P-Metric) Tire: The United States
version of a metric tire sizing system. The letter P
as the first character in the tire size means a
passenger vehicle tire engineered to standards set
by the U.S. Tire and Rim Association.
(A) Light Truck (LT-Metric) Tire: The United
States version of a metric tire sizing system. The
letters LT as the first two characters in the tire
size means a light truck tire engineered to
standards set by the U.S. Tire and Rim
Association.
(B) Tire Width: The three-digit number indicates
the tire section width in millimeters from sidewall
to sidewall.
Passenger (P-Metric) Tire
Light Truck (LT-Metric) Tire
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