Owner’s Manual

Black plate (48,1)
GMC Savana Owner Manual - 2013 - 2nd Edition - 9/25/12
10-48 Vehicle Care
Tire Designations
Tire Size
The following examples show
the different parts of a tire size.
Passenger (P-Metric) Tire
(1) 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.
(2) Tire Width
: The three-digit
number indicates the tire section
width in millimeters from
sidewall to sidewall.
(3) Aspect Ratio
: A two-digit
number that indicates the tire
height-to-width measurements.
For example, if the tire size
aspect ratio is 75, as shown in
item 3 of the illustration, it would
mean that the tire's sidewall is
75 percent as high as it is wide.
(4) Construction Code
: A letter
code is used to indicate the type
of ply construction in the tire.
The letter R means radial
ply construction; the letter D
means diagonal or bias ply
construction; and the letter B
means belted-bias ply
construction.
(5) Rim Diameter
: Diameter of
the wheel in inches.
(6) Service Description
: These
characters represent the load
index and speed rating of the
tire. The load index represents
the load carrying capacity a tire
is certified to carry. The speed
rating is the maximum speed a
tire is certified to carry a load.
Light Truck (LT-Metric) Tire
(1) 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 mean
a light truck tire engineered to
standards set by the U.S. Tire
and Rim Association.
(2) Tire Width
: The three-digit
number indicates the tire section
width in millimeters from
sidewall to sidewall.
(3) Aspect Ratio
: A two-digit
number that indicates the tire
height-to-width measurements.