What Is Tread? Does Tire & Width Actually Mean Two Different Things?

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If you look closely at automobile catalogs, you will see a number called “tread.

Although few people may pay attention to tread unless they are familiar with cars, the tread is one of the most important values that determine the performance of a car.

In fact, the tread has two meanings, each of which has a different role and what kind of performance it relates to.

I’ve always wondered, “What part of the car does tread refer to?” What does it mean that it has two meanings? You must be wondering, “What does tread mean?”.

In this article, we will explain in detail what tread is and what kind of performance difference is caused by different treads.

What Part Of The Car Is Tread?

Tread refers to the following two things:

  • Tire tread
  • Tread on the body structure

Let’s take a closer look at which part specifically we are talking about.

Tread On A Tire

The tire tread is the part of the tire that touches the ground. Since it is the only point where the car touches the ground, it is a very important part that transmits the car’s power.

It also serves to protect the inside of the tire from road impacts and trauma. Therefore, although a tire may appear to be made entirely of rubber, there are wires and other components inside the tire that support the structure.

In addition, most tires have grooves with various patterns on them, which are called “tread patterns.

Tread In The Car Body

The tread in a vehicle body is the distance between the left and right wheels, also known as “tread width”. The front and rear treads are called differently, with the front wheel being the front tread and the rear wheel being the rear tread.

Depending on the car model, the width of the front and rear treads are generally the same or slightly narrower on the rear wheels, because this improves turning and driving functionality.

The length of the tread width determines the characteristics of the car and changes the driving feel. Longer tread widths allow the car to turn in small circles, while shorter tread widths make the car more stable when driving in a straight line.

What Is A Tire Tread Pattern?

A tread pattern is a set of grooves carved into a tire. This is not a pattern for design considerations; the tread pattern allows for a variety of effects related to the driving of the car. Let’s take a closer look at the types and characteristics of tread patterns.

Various Tread Patterns To Suit The Usage Environment And Vehicle Characteristics

There are four basic tread patterns. What kind of groove pattern does each of them have and what effect does each have?

Rib Type

Ribbed grooves are horizontal to the direction of tire rotation. It is suitable for driving on paved roads and highways. It is characterized by excellent handling stability, low noise, and low rolling resistance.

Lug Type

The lug type is a groove carved perpendicular to the direction of tire rotation. It is suitable for driving on unpaved roads. It has excellent driving and braking power and is resistant to scratches.

Ribbed Lug Type

The rib lug type has the advantages of both the rib and lug type and is suitable for both paved and unpaved roads.

Block Type

The block type is a pattern of independent blocks carved in vertical and horizontal grooves. It has excellent grip performance on snowy or muddy roads and is stable. It is also characterized by high driving and braking power.

Based on these four basic types, there are now various designs of tread patterns.

Tires Without A Tread Pattern Also Exist

Slick tires used for racing, such as F1 tires, do not have a tread pattern. This is because the absence of a tread pattern provides a high grip on paved surfaces such as race circuits.

There are two main reasons why slick tires do not have a tread pattern.

The first reason is that the lack of a tread pattern allows for a more stable ride. The lack of grooves increases the tire’s ground contact area, which increases grip and improves turning and braking ability.

The second reason is that the tire does not sag due to increased rigidity. The absence of a tread pattern prevents the blocks from collapsing or sagging when force is applied to the surface, making the tire more resistant to distortion.

This also contributes to improved grip as a result.

What Is The Role Of The Tire Tread?

So far, we have learned more about tire tread patterns. So what role does the tread play when driving? Here we introduce the role of the tread.

Basic Role Of Tire Tread

The four basic roles of the tread are as follows:

1. Ensuring Driving Force

Driving force is the force required for a car to move forward. Tread plays a major role in enabling the car to accelerate.

2. Securing The Braking Force

Braking force is the force required to decelerate the car by braking. Tread improves grip and ensures the vehicle’s braking power.

3. Improved Turning Performance

The tread creates friction with the ground and prevents the car from sliding when cornering. This prevents the car from skidding when turning a curve and allows the car to firmly grip the road surface.

4. Improved Drainage

Braking distance increases on wet road surfaces. The tread effectively drains water and maintains a grip on wet surfaces.

Other Roles Of Treads

In addition to the four basic ones, there are a number of other roles that tread is expected to play in modern tires. Specifically, these roles include

Vibration Absorption

Tread patterns reduce vibration. Less vibration means a more comfortable ride and less fatigue when driving long distances.

Quietness

Vibrations caused by friction between the tires and the road surface are transmitted into the car, resulting in a “roaring” noise. This noise, known as “road-noise,” can be reduced by the tread, thus maintaining quietness.

Wear Resistance

Tire tread wears down due to friction with the ground. Since tread wear adversely affects driving, high wear resistance is required.

Improved Fuel Economy

Tires need to have a good grip, but a strong grip means high rolling resistance against the ground surface, which reduces fuel efficiency. This is why fuel-efficient tires and eco-friendly tires have recently emerged.

Fuel-efficient tires use a tread pattern that reduces resistance without compromising grip, leading to improved fuel economy.

When The Tire Tread Wears Out?

Tires gradually wear down due to friction with the road surface and the tread grooves become shallower. What are the effects of a worn tire tread surface?

Dangers Of Tires With Smooth Tread

When the tread grooves become shallow and slippery, the following four negative effects can occur

1. Increased Tendency To Slip In The Rain

Without tread grooves, tires become slippery on wet road surfaces. This lowers the frictional force and makes the tires more likely to slip in the rain, which is dangerous.

2. Increased Braking Distance

As the tread grooves become shallower, the gripping power is reduced. This will increase the distance from the time you start braking to the time the car actually stops, increasing the possibility of an unexpected accident.

3. Increased Likelihood Of Punctures

The tread is worn out and cannot withstand the driving load, increasing the probability of a tire puncture.

4. Reduced Quietness

As the tread surface wears down, vibrations caused by friction with the ground are more easily transmitted and cause noise.

Danger Signs That Can Be Determined From The Tread

Danger signs can be seen when the tread shows any of the following:

  • Slip signs
  • Scratches or cracks
  • Foreign objects are stuck in the tread

The slip sign is a raised area at the bottom of the tire grooves that appears when the groove depth reaches 1.6 mm.

However, tires should not be replaced when the slip sign appears, but rather when “3.2mm remaining,” which is twice the 1.6mm, is the recommended replacement time.

The reason for this is that 3.2 mm is the depth of the grooves at which tire performance declines significantly. If any of the above three conditions are observed, it is dangerous and the tire should be replaced immediately.

What Does The Tread Width Of The Vehicle Body Have To Do With It?

We have seen that the tread of a tire is related to its grip and other characteristics. In contrast, the tread of a car body is a value related to the characteristics of the car itself. What difference does a change in tread width make to the characteristics of the car?

What Changes When Tread Width Changes?

The tread width makes a difference in handling when driving. Specifically, they are as follows

When The Tread Width Is Wide

The ability to withstand centrifugal force when driving around curves is greater, and the vehicle is more stable when cornering. However, stability when traveling in a straight line is reduced.

When Tread Width Is Narrow

The sense of stability when traveling in a straight line is increased, and the ride feels more comfortable. On the other hand, instability increases when turning curves.

One thing that is largely related to tread width is the wheelbase. The wheelbase is the length from the center of the front wheels to the center of the rear wheels when the car is viewed from directly across.

The wheelbase divided by the average of the front and rear tread widths is called the wheelbase-tread ratio. This value determines the driving performance of the car and makes a difference in ride comfort and handling.

Specifically, the closer the value is to 1, the more maneuverable the car is in cornering, and the closer it is to 2, the more stable it is in a straight line.

Thus, it is possible to choose whether cornering performance or stability in a straight line is more important, based on the wheelbase/tread ratio value.

Conclusion

In this article, we have discussed car treads in detail. We have learned that the tread, or grooves in tires, play an important role in ensuring braking power and improving drainage.

Tire treads should be inspected regularly to check for any abnormalities and to ensure safe driving.

We also found that the tread width of the vehicle body makes a difference in handling. However, there are some aspects that cannot be determined by numbers alone.

If you are planning to buy a new car, why not look for a car that feels comfortable to drive while also referring to the tread values?