Tread designs
The real purpose of a tire is to get a grip on the road. The
Ideal tire is one that wears little, holds the road well to
provide sure handling and braking, and provides a cushion
from road shock. The ideal tire should also provide
maximum grip on dry roads, wet roads, and snow and
ice, and operate quietly at any speed. This is a tall order,
so tire manufacturers compromise on one or two of these
qualities for the sake of excelling at another. A tire's tread
design dictates what the tire will excel at.
There are basically three categories of tread patterns:
directional, nondirectional, and symmetric asymmetric.
A directional tire is mounted so that it revolves in a
Particular direction. These tires have an arrow on the
Sidewalls that show the designed direction of travel. A directional
tire offers good performance only when it is rotating
in the direction in which it was designed to rotate
(Figure 42-5). A nondirectional tire has the same handing
Qualities in either direction of rotation. A symmetric
tire has the same tread pattern on both sides of the
tire. An asymmetrical tire has a tread design that is different
from one side to the other. As5rmmetrical tires are
typically designed to provide good grip when travelling
straight (the inside half) and good grip in turns (the outside
half of the tread). Most asymmetric tires are also
directional tires.
The number and size of the blocks, sipes, and grooves
on a tire’s tread not only determine how much rubber
contacts the road and how much water can be displaced,
they also determine how quiet the tire will be during
travel. The more aggressive the tread, the more noise it
will make. This statement is especially true if the tire’s
tread is made of a hard compound. Softer tires typically
make less noise but wear more quickly. Soft tires also adhere
to the road better.
Channels are cut into a tire’s tread to allow water to
move away from the tire's direction of travel. Obviously
the deeper the channel, the more water the tire can
move. The disadvantage of these channels is decreased
road contact.