The US Government has established the UTQG, the Uniform Tire
Quality Grading, to assist consumers in their purchase of tires.
Basically it's another tool to be used besides the opinions you
gather from trusted friends, mechanics and whatever other sources
you may have at your disposal. The key to using this system is
to understand that it is a relative comparison system. The UTQG
is not a safety rating and not a guarantee that a tire will last
for a prescribed number of miles. Under UTQG, manufacturers use
three criteria to grade tires: treadwear, traction and temperature.
The information is right where you need it when buying the tire:
- On the paper label affixed to the tread
- On the tire molded into the sidewall
The treadwear grade is a comparative rating based on the
wear of a tire when tested carefully under controlled conditions.
For example the useful tread on a tire graded 400 should last twice
as long as a tire graded 200. However, another tire manufacturer
may grade a comparable design 300, so a grade of 150 would last
just half as long under their grading scheme. The lesson learned is
to not use one manufacturer's grade versus the other, but instead
to compare tire grades within a given brand. Actual treadwear
performance can vary tremendously according to the tire's
real-world use. Variations in driving habits, service practices
(most importantly air pressure maintenance), road conditions and
climate affect tire life.
Traction grades represent the tire's ability to stop on wet
pavement as measured under controlled conditions on asphalt and
concrete test surfaces. As of 1997, the traction grades from highest
to lowest are "AA","A","B" and "C". A tire graded "AA" may have
relatively better traction performance than a tire graded lower,
based on straight-ahead braking tests. The grades do not take into
consideration the cornering or turning performance of a tire.
Temperature grades represent a tire's resistance to heat and
its ability to dissipate heat when tested under controlled laboratory
test conditions. The grades from highest to lowest are "A","B" and
"C". The grade "C" corresponds to the minimum performance required by
federal safety standard. Therefore, the "A" tire is the coolest
running, and even though the "C" tire runs hotter it does not mean it
is unsafe. The temperature grade is established for a tire that is
properly inflated and not overloaded. |
