What do the numbers and letters on the tire mean?
The tire is the easiest part to wear and replace in auto parts. Its importance and expendability are self-evident. But you will find that when you see many other numbers and letters on the tire, you don’t understand the meaning.
What does each kind of mark on the tire mean?
1. Section width
Taking 205/60 R16, 91V as an example, 205 refers to the width of the tire section, which is the width between the two sidewalls (in millimeters).
The width of the tire mainly affects the contact area of the tire and the ground. Generally speaking, the width of the mini car is between 125-155mm, the small car is between 165-195mm, and the compact car is between 195-225mm.The tire is wider and the area of natural contact with the ground is increased. It will definitely improve the grip and also directly improve the performance of the brake. However, there are disadvantages. More friction surfaces will inevitably bring more noise and resistance, which will cause greater noise and fuel consumption. The grip is also related to the composition of the tire. In general, the softer the material, the stronger the grip,
but the worse the durability.
Therefore, the width is not as large as possible, because the wider the tire resistance, the higher the fuel consumption, the slower the acceleration. Therefore, we cannot blindly widen the tires, we must coordinate the power and economic performance of the vehicle. Choosing a wider tire is indeed helpful for handling and other performances, but it is recommended to match a wider tire with sufficient power, otherwise the power is small but the tire width will cause greater troubles for fuel consumption and the feel of the steering wheel.
2. Tire flatness ratio
60 is the flat ratio. The flat ratio refers to the ratio of the tire's broken height to the tire's section width, that is, its thickness divided by the width is 60%, and the thickness of the tire can also be reversed, so the smaller the flat ratio means the tire The thinner.
High aspect ratio tires are relatively comfortable because of their long sidewalls and strong cushioning capacity, but they have a poor feeling on the road and weak resistance to rolls when cornering. It's like you're wearing a pair of shoes with thick soles and good elasticity. It's very comfortable when walking or stepping on potholes, but it's easy to stomp once you are running.
Low-flat-ratio, large-inner-diameter tires have shorter sidewalls and wider treads, so the ground area is large, the tires can bear a lot of pressure, the feedback to the road feel is very clear, and the ability to resist roll when turning is strong. The handling of the vehicle is excellent. Just like you are wearing a pair of shoes with very thin soles, any feedback on the road surface is very clear. You will have a distinct feeling when stepping on a small stone. Obviously, wearing such shoes will be very uncomfortable when walking. But if you are allowed to run on the runway, your feet can fit the road very well, shoes are like a part of your feet, and will run quickly.
3. Radial tire and wheel diameter
Our common tires are denoted by R, which is the radial tire, commonly known as "steel wire tire". The radial tire refers to the tire's internal cord weaving arrangement direction at a 90-degree angle to the centerline of the tread, which is named after the meridian on a globe. Generally, this kind of tire has a steel layer on the top of the tire, which can withstand large internal pressure stress, the tread is not easy to deform, and has good ground grip and stability, suitable for high-speed driving. Cars now use radial tires.
Compared with ordinary diagonal tires, radial tires have greater elasticity and good wear resistance, which can increase the service life of tires by 30-50%, have low rolling resistance, can reduce automobile fuel consumption by about 8%, and have good adhesion performance and good cushioning performance. It has the advantages of large carrying capacity and is not easy to puncture. The disadvantage is that the sidewall is easy to crack, and due to the large side deformation, the lateral stability of the car is poor, and the manufacturing technical requirements and cost are high.
The number behind R represents the diameter of the hub, in inches. Therefore, when choosing a tire, it can be matched according to the size of the hub.