Perhaps the biggest
mistake a consumer can make when replacing tires is not using the correct size.
On the sidewall of your tire, you'll find a code that tells the tire's size and
capabilities. Here's a sample code:
P195/60R16 63H M+S
P - Type of tire
195 - Width of the
tire across the tread in millimeters
60 - Aspect ratio of
the sidewall compared to the width
R - Radial
construction
16 - Diameter of the
rim in inches
63 - Tire's load
rating
H - Tire's speed
rating
M+S - Tire is suitable
for all-season driving
If the tire-size code
starts with LT instead of P, it means the tire is a light-truck tire.
Light-truck tires are designed to have higher-load carrying capacities and are
usually found on pickups and SUVs. These vehicles are not required to have LT
tires, and in many cases, the original-equipment specification calls for
passenger-car tires.
The speed rating
translates into the tire's ability to dissipate heat, or prevent heat build-up.
Heat is a tire's enemy. The more heat, the faster the tire wears, and the
faster a tire might break down. A tire with a higher speed rating can dissipate
more heat on long highway trips. If a consumer were to spend little time on the
highway, the speed rating might not be an important factor in choosing a
replacement tire.
Tires are speed rated
from 99 to 186 miles per hour (159.3 to 299.3 kilometers per hour). The most
common speed ratings are T (118 miles per hour or 189.9 kilometers per hour)
and H (130 miles per hour or 209.2 kilometers per hour). Both of those ratings
clearly exceed the nationally posted speed limits and would make excellent
long-distance highway tires. If a consumer were to drive only in urban
situations at low speeds, a tire with an S (112 miles per hour or 180.2
kilometers per hour) speed rating might be completely acceptable.
Another important
factor in choosing a replacement tire is the load rating. The load capacity
number on the tire-size code indicates the load-carrying capacity of that
single tire. When selecting replacement tires, consumers have to be careful not
to select a tire with a lower load-carrying capacity.
Regardless of a tire's
speed rating, load-carrying ability, size and construction, traction are the
keys to safety. A common mistake is to select a tire without considering its
ability to hold the road. Savvy consumers will balance a tire's traction in dry
conditions, in wet conditions and in the snow. If you desire a high-performance
tire but live in northern climates, consider a "winter" tire for
driving in the snowy season. If you live where the weather is warm all year, a
touring tire may suit your needs just fine.
Most consumers will
make the mistake of waiting until spring to get new tires. As a tire wears out,
dry traction generally increases and wet and snow traction decrease. So the
best time to buy new tires is not in the spring, but in the fall.
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