(3) Rib-and-lug pattern

This pattern combines the rib and lug patterns to provide stable driving performance on both paved and unpaved roads.

The rib pattern running along the center of the tire stabilizes the vehicle by minimizing tire side-slipping, while the lug pattern on the edges of the tire enhances driving and braking performance. The lug portion of the pattern is more susceptible to uneven wear.

(4) Block pattern

In this pattern, the tread is divided into independent blocks. Used on most snow tires and studless tires, the block tread pattern is now coming to be used on radial-ply tires for passenger cars as well.

The block pattern provides better driving and braking performance.

The block pattern reduces slipping and skidding on muddy or snow-covered roads.

The tires tend to wear faster than those with the rib and lug patterns.

Rolling resistance is slightly greater.

The tread is susceptible to unusual wear, especially on hard surfaces.

Unidirectional Pattern Tires

These are tires with a tread pattern, which has directionality with respect to the direction of rotation. Lateral grooves in the tire tread are given directionality in order to improve performance on wet roads, making it easier for the tires to drain off water. The performance of these tires on wet roads worsens if they are mounted in the wrong direction.

2. Pattern noise

Pattern noise is the most distinctive operating sound of the tire. The tread grooves coming into contact with the road surface contain air, which is trapped and compressed between the grooves and the road surface. When the tread leaves the road surface, the compressed air bursts out of the grooves, generating noise. Pattern noise increase if tread design is such that air is more liable to be trapped in the grooves.

The block or lug tread pattern, for example, is more likely to generate noise than the rib pattern. The pitch (frequency) of the noise rises as the vehicle speed increases. Since pattern noise thus depends on tread pattern, the pattern can be designed to minimize this. What appears to be a simple repetitive lug and zigzag pattern, for example, may contain subtle variations in pattern spacing.

Tires are installed on the vehicle together with disc wheels. Vehicles ride on pneumatic tires filled with pressurized air. Tires are the only vehicle components that come into direct contact with the road surface. If the tire air pressure is improper, this can cause abnormal wear and lower the driving performance. Tires perform the following functions:

The tires support the overall weight of the vehicle.

The tires directly contact the road surface and therefore transmit the vehicle’s driving and braking forces to the road, thus controlling starting, acceleration, deceleration, stopping, and turning.

The tires attenuate (reduce) shock caused by irregularities in the road surface.

Outline Construction

Construction

(1) Tires The types of tires are tubed tires and tubeless tires. Also, there are radial tires and bias tires, both of which comprise the following parts.

<1>Tread

<2>Belt (rigid breaker)/Breaker

<3>Carcass (cross plies)

<4>Inner liner

<5>Bead wire There are also other types, such as compact spare tires (temporary tire types) used for punctures and other emergencies, and run-flat tires on which you can drive a certain distance even with a puncture.

(2)Tire size The size, performance, and the construction of the tire are indicated on the sidewall of a tire. The diagram on the left shows the names of the sizes of the various areas of a tire.

(3)Disc wheels

Tread Patterns

1. Types of tread patterns

A wide variety of patterns are molded into the tread both to help drain away water, and to cope with various factors dictated by the conditions of the road surface and the type of the vehicle being used.

(1)Rib pattern

The rib pattern consists of several parallel zigzag grooves that run along the circumference of the tire. This pattern is best suited for traveling on paved surfaces at high speeds and is used for a wide variety of automobiles, from passenger cars to buses and trucks.

The rib pattern minimizes the resistance of the tire to rolling.

Greater resistance to side-slipping provides good vehicle controllability.

Tire noise is reduced.

Traction is somewhat inferior to that of tires with the lug pattern.

(2) Lug pattern

The grooves in the lug pattern run at roughly right angles to the tire circumference. Frequently used on construction machinery and truck tires, this tread pattern is suited for driving on unpaved roads.

The lug pattern provides good traction.

Tire rolling resistance is somewhat high.

Resistance to side-slipping is smaller.

Tread in the lug area is susceptible to uneven wearing.