Cadillac DTS 2011 Owner's Manual page 363

(C) Aspect Ratio A two digit number that
:
indicates the tire height to width measurements.
For example, if the tire size aspect ratio is 60, as
shown in item C of the illustration, it would mean
that the tire's sidewall is 60 percent as high as it
is wide.
(D) Construction Code
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
represent the load index and speed rating of the
tire. The load index represents the load carry
capacity a tire is certified to carry. The speed
rating is the maximum speed a tire is certified to
carry a load.
A letter code is used to
:
These characters
:
Light Truck (LT Metric) Tire
(A) Light Truck (LT Metric) Tire
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.
The United
:
6-53