Chevrolet Spark EV 2014 Owner's Manual page 271

The following is an example of
a typical passenger vehicle
tire size.
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.
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 3 of the illustration, it would
mean that the tire's sidewall is
60 percent as high as it is wide.
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 carrying capacity a tire
is certified to carry. The speed
rating is the maximum speed a
tire is certified to carry a load.
air inside the tire pressing
A letter
outward on each square inch
of the tire. Air pressure is
expressed in kPa (kilopascal)
or psi (pounds per square inch).
combined weight of optional
accessories. Some examples of
optional accessories are, electric
drive unit, power windows,
power seats, and air
conditioning.
These
of a tire's height to its width.
The amount of
The
The relationship