Hummer 2008 H2 - Manual (Page 393)

(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 5-61 and Loading Your Vehicle on page 4-44.
Tire Size
The following examples show the different parts of
a tire size.
(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.
(C) 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 C of the light truck (LT-Metric)
tire illustration, it would mean that the tire’s
sidewall is 75 percent as high as it is wide.
(D) 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.
(E) Rim Diameter : Diameter of the wheel in
inches.
(F) Service Description : The service description
indicates the load range and speed rating of a
tire. The load index can range from 1 to 279.
Speed ratings range from A to Z.
Light Truck (LT-Metric) Tire
5-57