Tire pattern is only used to increase friction? of course not

Many people think that the role of tread patterns is to increase friction. I don't know where this remark comes from. However, I tell you today: The tire pattern is used to increase the friction, it is really wrong!

Tire pattern: "I do not increase friction."

If the role of the tread pattern is to increase the friction, why is there no pattern on the fast cornering F1 racing tyres? Is F1 racing without friction? On the contrary, F1 cars need a lot of friction, so they use bare-boned tires. Because there is no tread pattern, the contact area between the tire and the ground is greater and friction is greater.

If you are good at physics in middle school, then you are sure to be puzzled at this time. The friction formula given by middle school physics is: f = μN. The friction is only related to μ (friction coefficient) and N (positive pressure), and The contact area is irrelevant. However, this formula is given in macroscopic terms. From the microscopic point of view, the frictional force is related to the contact area.

At the microscopic scale, the surface of the object is rough and uneven. When two objects come into contact with each other, their "real contact area" is far smaller than the contact area you see. The "real contact area" controls the friction to a certain extent. size.

"Microscopic rough glass surface"

As you can imagine, the contact between two objects looks like the "snapping" of two rough surfaces. As the pressure increases, the object deforms, the degree of "bite" increases, and the friction increases, so the friction is related to the contact area.

Those high-powered sports cars will use wider tires, which also proves from the side that the friction is related to the contact area, otherwise it would not be good for Lamborghini to put on four bicycle tires?

However, this is only a very rough speculation. Friction is actually a very complicated thing, and its specific model is difficult to calculate.

Since the friction is related to the contact area, why does the household car not use the bald tire to increase the friction? Here, we have to say the most important role of the tread pattern: the most important role of the tread pattern - drainage!

When driving on a rainy day, the front of the tire in contact with the tire will produce a certain pressure to the tire. For example: We put our hands into the tank and stir the water. We will find that the water will give back a reaction force. However, the dynamic pressure generated by water on the tire is proportional to the square of the speed. As the tire's rotational speed increases and the dynamic pressure balances the tire's load, the tire completely loses contact with the road and floats on the water film. Loss of friction with the ground. At this point the car will slip out of control and dangerous. Therefore, we need the tread pattern to quickly discharge the water from the front of the tire from both sides to keep the tire in contact with the road surface.

Although the use of bald tires does increase the friction on dry asphalt roads, the weakness of the bald tires is exposed on rainy days. Therefore, in order to take into account all-weather road conditions, the family car is equipped with four-season tires with patterns.

The same is true for F1 racing cars. If it starts to rain in the race, the driver will quickly return to the pits and replace the rainy tires with patterns.

With the increase of mileage, the tires are also worn. If the tread pattern is too shallow, it will affect the drainage capacity of the tire. In the rainy season, we should learn to detect the wear of the car's tires for safety. Then, how should we judge the depth of the tread pattern?

In the groove of the tread pattern, there will be some raised marking points. When your tire pattern is flush with the marking point, you need to change the tire immediately. At this time, the tread pattern is not enough to drain quickly and is slippery. The road is very dangerous.

In addition, tire treads have the effect of reducing noise and fuel economy, but the most important feature of tire treads is drainage. If there are still people in the future who can increase the friction on the tire tread theory, then you tell him: Hey!