Buick 2010 Lacrosse Owner's Manual page 335

The three digit
number indicates the tire section
width in millimeters from
sidewall to sidewall.
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.
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.
Diameter of
the wheel in inches.
characters 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
air inside the tire pressing
outward on each square inch
of the tire. Air pressure is
expressed in psi (pounds per
square inch) or kPa (kilopascal).
means the combined weight
of optional accessories.
These
Some examples of optional
accessories are, automatic
transmission, power steering,
power brakes, power windows,
power seats, and air
conditioning.
The amount of
This