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(F) Uniform Tire Quality Grading (UTQG) : Tire
manufacturers are required to grade tires based
on three performance factors: treadwear, traction
and temperature resistance. For more information
see Uniform Tire Quality Grading
on page 6‑79
.
(G) Maximum Cold Inflation Load Limit
:
Maximum load that can be carried and the
maximum pressure needed to support that load.
Tire Size
The following illustration shows an example of a
typical passenger (p‐metric) vehicle tire size.
(A) 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.
(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‐w idth 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
: 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
: These 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.
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