Tires
Round-shaped elastic rubber products that roll on the ground and are assembled on various vehicles or machinery. Usually installed on a metal rim, it can support the body, buffer external impacts, achieve contact with the road and ensure the driving performance of the vehicle. Tires are often used under complex and harsh conditions. They are subject to various deformations, loads, forces, and high and low temperature effects when driving. Therefore, they must have high load-bearing performance, traction performance, and cushioning performance. At the same time, high wear resistance and flex resistance, as well as low rolling resistance and heat generation are also required. Half of the world's rubber consumption is used in tire production. Tires usually consist of three parts: outer tire, inner tube, and belt. There are also those that do not require inner tubes. The inner layer of the carcass has a rubber layer with good air tightness and requires a special rim. The structure of tires in various countries around the world is developing in the direction of tubeless, radial structure, flat (the ratio of tire section height to width is small) and lightweight. The outer tire is composed of tread, sidewall, buffer layer (or belt layer), ply layer and bead. Used to withstand various forces. The sidewall is the rubber layer on the outside of the tire's side ply that is used to protect the carcass. The ply is a layer of fabric in the carcass composed of parallel rubber cords. It is the stress-bearing skeleton layer of the tire and is used to ensure that the tire has the necessary strength and dimensional stability. The buffer layer (or belt layer) is the rubber layer or rubber layer between the bias tire tread and the carcass. It is used to buffer external impact forces, protect the carcass, and improve the adhesion between the tread and the ply. The bead is the part of the tire installed on the rim. It is composed of a bead core and a bead wrapper and plays a role in fixing the tire. The specifications of the tire are expressed in dimensions such as outer tire diameter D, bead inner diameter or rim diameter d, section width B and aspect ratio (tire section height H/tire section width B). The unit is generally inches (in) (1in=2.54 cm). Car tires are composite products of rubber, fiber materials and metal materials. The manufacturing process is a comprehensive process of mechanical processing and chemical reactions. Rubber and compounding agents are mixed and extruded to form treads; cords are rolled, cut, and bonded to form cord tubes or cord rolls; steel wires are plied and encapsulated and formed into beads; then all semi-finished products are put on the forming machine They are combined into a tire blank and vulcanized in the metal mold of the vulcanizing machine to make the finished tire.
Supplement: Car tire knowledge
A journey of a thousand miles begins with a single step. As the four legs of a car, the importance of car tires is self-evident. When a car is driving at high speed, tire failure is what all drivers worry about most and is the most difficult to prevent. It is also an important reason for sudden traffic accidents. Tires are an important part of the car's driving system, just like the shoes we wear. In addition to choosing the right ones according to their functions (don't wear formal leather shoes to play tennis or sports shoes to dance ballroom), you also need to know how to care for them. Let’s explore the mysteries of tires together.
The common classification method of tires is to divide them into bias tires and radial tires according to their structure. The fundamental difference between radial tires and bias tires is the carcass. The carcass of bias-ply tires is made of diagonally crossed ply layers; while the carcass of radial tires is made of a polymer multi-layer cross material, with the top layer being several layers of steel belt cords made of steel wires, which can reduce the tire from being punctured by foreign objects. probability.
In terms of design, bias-ply tires have many limitations. For example, due to the strong friction of the crossing cords, the carcass is prone to heat, thus accelerating the wear of the tread pattern, and its cord layout It also cannot provide excellent control and comfort; the steel belt in the radial tire has good flexibility to adapt to the irregular impact of the road surface, and is durable. Its cord structure also means that when the car is driving There is much less friction than bias lines, resulting in longer tread life and better fuel economy. At the same time, the characteristics of the radial tire itself make it possible for the tire to be tubeless. Tubeless tires have a recognized advantage, that is, when the tire is punctured, it does not burst like a bias-ply tire with an inner tube (which is very dangerous). Instead, it allows the tire to maintain air pressure for a period of time, improving the safety of the car. driving safety. In addition, radial tires have better grip than bias-ply tires.
The tires we are talking about below only refer to the radial tires commonly used in cars, commonly known as tubeless tires or atomic tires.
1. How to identify tire marks
Tires are important parts of cars. There are more than 10 kinds of marks on car tires. Correct identification of these marks is very important for tire selection, use and maintenance. It is also important for ensuring driving safety and safety. Extending the service life of tires is of great significance.
Tire specifications: Specifications are symbolic data of tire geometric parameters and physical properties. Tire specifications are often represented by a set of numbers. The first number indicates the tire section width, and the latter number indicates the rim diameter, both in inches. The letters or symbols in the middle have special meanings: "x" represents high-pressure tires; "R" and "Z" represent radial tires; "one" represents low-pressure tires.
Layer: The tier refers to the nominal number of plies in the rubber layer of the tire, which is not exactly the same as the actual number of plies. It is an important indicator of tire strength. Levels are marked in Chinese, such as level 12; levels are marked in English, such as "14P." R" is the 14-layer pole.
Cord material: Some tires are marked separately, such as "nylon" (NYLON), which is usually marked after the layer; some tire manufacturers mark it after the specifications, expressed by the first letter of Chinese Pinyin , such as 9.00-20N, 7.50-20G, etc., N represents nylon, G represents steel wire, M represents cotton thread, and R represents rayon.
Load and air pressure: Generally, the maximum load and corresponding air pressure are marked. The load is in kilograms. The air pressure is the tire pressure in kilopascals.
Rim specification: Indicates the rim specification that matches the tire. Convenient for practical use, such as "Standard Rim 5.00F".
Balance mark: Made of colored rubber in the shape of a mark, printed on the sidewall, indicating that the tire is the lightest here. When assembled, it should be facing the valve to ensure the balance of the entire tire.
Rolling direction: The pattern on the tire is particularly critical for water drainage and anti-skid during driving. Therefore, off-road vehicle tires with asymmetric patterns are often equipped with arrows to mark the rolling direction to ensure the adhesion, anti-skid and other properties of the design. If installed incorrectly, it will be counterproductive.
Wear limit mark: Rubber strips and blocks are used on one side of the tire to mark the wear limit of the tire. Once the tire wear reaches this mark, it should be replaced in time, otherwise the tire will burst midway due to insufficient strength.
Production batch number: a set of numbers and letters indicating the year, month and quantity of the tire. For example, "98N08B5820" means the 5820th tire produced by Group B in August 1998. The production batch number is used to identify the tire's condition and storage time.
Trademark: A trademark is the logo of a tire manufacturer, including trademark words and patterns. It is generally prominent and eye-catching and easy to identify. Most of them are marked in conjunction with the name of the manufacturer.
Other marks: such as product grade, production license number and other ancillary marks. It can be used as reference and information when choosing.
Tire markings are generally relatively standardized. Once they are clearly identified, you can purchase and use them with confidence.
The following is a common method of expressing tire specifications:
Example: 185/70R1486H
185: Tread width (mm)
70: Aspect ratio (tire height ÷ tire width)
R: Radial structure
14: Steel rim diameter (inches)
86: Load index ( Indicates that the corresponding maximum load is 530 kg)
H: Speed ??code (indicates that the maximum safe speed is 210 km/h)
2. How to choose tires
Understanding the basic knowledge of tires is only the first step. The next step is to consider how to buy tires suitable for your car. When choosing, in addition to understanding the tire specifications required for your car In addition, we should also pay attention to the following aspects.
First of all, give priority to the original tires. The original tires are the ones that best match the speed of the car and the maximum load of the car. Therefore, theoretically, they should be given priority when replacing tires.
Secondly, pay attention to the tire pattern. In addition to the aesthetic effect, the pattern on the car tire also has a great impact on the performance of the tire. Cars that often drive in Shenzhen should choose tires with better drainage, such as regular small-block patterns; while cars that need to go off-road and run long distances can choose large-block patterns.
Finally, if you are not satisfied with the original handling of the vehicle, you can consider replacing tires with a lower aspect ratio. For many models, one of the most effective ways to improve the appearance and handling performance of the vehicle is to replace them. Low aspect ratio tires. Each style of tires has their specific functions. Therefore, when choosing tires, you should ask clearly which style of tires is suitable for what kind of driving habits. This way, the car will be safer when driving and the money spent on tires will be more. worth.
When buying tires, don't just look at the price. You should ask professionals for advice. They will help you accurately match the appropriate tires.
When choosing tires, be careful not to mix different types of tires. For example, put tires that are more suitable for off-road vehicles with tires for general cars, or put tires that are more suitable for off-road vehicles together. A mix of directional sports car tires and general tires.
Of course, you should try to avoid retreaded tires when purchasing. Currently, Shenzhen, especially some street shops, often sell some retreaded tires as substandard ones. Consumers must pay attention when purchasing. The method to identify retreaded tires is very simple: the most common is to observe the color and gloss of the tires. The color and gloss of retreaded tires are relatively dim, so do not blindly buy such tires.
Professional technicians identify tires through the signs on the tires. There are some raised signs on car tires, indicating the tire model and performance. These are the breakthrough points for identifying retreaded tires. The marks on retreaded tires are re-attached after retreading, while the marks on new tires are integrated with the tires. The identification method is to scratch these marks with your fingernails. Generally, the marks on retreaded tires are not very tightly attached. , the ones that can be caught must be retreaded tires.
In recent years, the development trend of foreign passenger car tires is the increasing use of tires with large width, large inner diameter and low aspect ratio. At present, domestically produced cars mostly use tires with small width, small inner diameter and high aspect ratio. High aspect ratio tires have relatively high comfort due to their long sidewalls and strong cushioning capacity, but they have poor road feel and weak lateral resistance when turning. On the contrary, tires with low aspect ratio and large inner diameter have shorter sidewalls and wider treads. Therefore, the ground contact area is large, the pressure that the tire can withstand is also large, the tire responds very sensitively to the road surface, and has strong lateral resistance when turning, which greatly enhances the vehicle's controllability. At present, the tires with the largest aspect ratio used in domestic mass-produced cars are 225/55R16, while the tires of many imported luxury cars or sports coupes have reached 225/45R17, and some have even reached 245/40R18. After the vehicle is equipped with tires with large width, large inner diameter and low aspect ratio, in addition to strong maneuverability, the appearance and visual effects also give people a very powerful feeling. Generally speaking, the tires equipped on vehicles when they leave the factory are the best specifications selected by the manufacturer after repeated testing. If a car owner wants to change the tire size, he must do it under the guidance of a professional and cannot do it casually, because it involves many problems, and a little negligence may cause harm to driving safety. In addition, low aspect ratio tires will appear more "delicate" and should be paid more attention to and taken care of during use.
What is the speed rating of a tire?
Answer: Formally speaking, a speed rating indicates the maximum speed at which a tire can carry a specified load under specified conditions. The letters A to Z represent the tire's certified speed rating from 4.8 km/h to 300 km/h.
Commonly used speed levels are:
Q 160 km/h V 240 km/h
R 170 km/h W 270 km/h
S 180 km /h Y 300 km/h
T 190 km/h Z ZR The speed is higher than 240 km/h
H 210 km/h ZR If the tire specification mark appears in the instruction manual ZR. For example, P275/40ZR17 93W, then the maximum speed level (the "W" in "93W") is 270 km/h.
In recent regulations to standardize tire markings, the instructions for use of all grades except the continuously variable Z speed grade include speed symbols and load factors. For example: P225/60R15 95H is the tire instruction manual, indicating that the maximum load capacity of the tire is 690 kg and the maximum speed rating is 210km/h.
Q: I plan to buy two new tires. Should they be installed on the front or rear wheels?
Answer: Rear wheels. If your front wheels spin first when maneuvering a tight corner on wet pavement, your car will continue to go in a straight line even as you turn. This amounts to understeer, which can be achieved by slowing down and then steering around the corner. This will allow the car to return to the driveway.
But if the rear wheel slips first, the car may spin, which is equivalent to oversteer and will only be more difficult to control. This requires you to make quick and accurate steering corrections in the opposite direction of the curve, which is not a natural reaction. It's easier to control understeer than oversteer.
To keep records, the best option is to purchase four new tires of the same brand, specification, and model at one time when replacing tires.
Q: If I only want to buy one tire, what product should I buy and where should it be installed?
Answer: The only good reason to buy just one tire is to replace a tire that has been damaged by an accident or road hazard, otherwise all four tires in the set are good. When purchasing, look for the same specification, model, brand and tread pattern design as the replacement tires. Replace all-season tires with all-season tires. Replace snow tires with snow tires. Replace H-speed tires with H-speed tires. In this way, you will enjoy a safer and more comfortable driving experience.
Q: Tire usage tips
① Ordinary car tires have no directionality and can in principle be interchanged left and right (unlike F1 racing tires which have strict directionality);
② It is recommended that the front and rear tires of Jetta cars be interchanged every 20,000KM (Feixian: The literature I read says that the rear wheels can be moved parallel to the front, and the front wheels can be moved crosswise to the rear. The reason is that in general The wear of the front tire is greater than that of the rear tire, because there is steering action at the front; the right tire wear is greater than the left tire, because the road has a curvature, and the tire travel on the right side will be longer);
③ The time-dependent aging of the tires is not obvious. , whether aging, wear or mileage and road surface conditions account for most of the reasons; that is, the driving age cannot be used as the criterion for judging whether to replace tires, but the kilometers traveled should be used as the main parameter, and the most important thing is the wear degree of the tires. (Feixian: It’s a pity that I can’t find a picture that can clearly indicate which pattern is worn to what extent and must be replaced as soon as possible. Please look for it);
④ Blindly enlarging the wheel hub is not possible. Well, the braking effect will become worse. Because the braking force of the braking mechanism may be insufficient;
⑤ Using tires that are too wide will increase comfort and stability, but fuel consumption will increase and braking will also have problems;
⑥ Tires should be used and replaced in pairs as much as possible to ensure the left and right balance of the vehicle by keeping a pair of tires with similar wear and working conditions (Feixian: It should be recorded in detail when each tire was replaced, the mileage and Whether it has been repaired so that exchange and replacement can be arranged.
I also know which tire is in which working condition);
⑦ The parameters and indicators of the spare tire of a general car (except luxury cars) are exactly the same as the four tires in use, which can be used when there is a tire problem. Use them interchangeably. However, it is strongly recommended to replace the worn tire after repairing it. The spare tire still serves as a spare tire, keeping this tire intact for a long time in case of emergency. If you use the repaired tire as a spare tire, it may happen that the tire is flat when you want to use the spare tire due to slow deflation. Furthermore, the spare tire is newer and used in pairs with old tires, which also destroys the above-mentioned principle of using in pairs.
Tire markings
According to national standards, the production number, manufacturer's trademark, size specifications, ply, maximum load and corresponding air pressure, carcass ply should be marked on both sides of the tire. Chinese pinyin code, installation requirements and driving direction signs, etc.
The carcass cord material is expressed in Chinese Pinyin. Such as M-cotton cord, R-rayon cord, N-nylon cord, G-steel cord, ZG-steel radial cord tire.
The side of the tire is marked with symbols such as "△", "-", "□" or words such as "W" and "D", indicating the lightest part of the tire. When installing the inner tube, it should be The valve is installed in alignment with the mark to even out the weight around the tire and keep the tire stable when rotating at high speed. The arrow "" indicates directional tires. Install in the direction of the arrow for rotation.
High-pressure tires are represented by D5B, D represents the nominal outer diameter of the tire, and B is the cross-sectional width of the tire in inches. "X" indicates high-pressure tires.
Low-pressure tires are represented by B-d, B is the tire section width, d is the rim diameter, and "-" represents low-pressure tires. Since section B is approximately equal to section height H, the size d of the installed rim can be calculated as d=D-2B. For example, Audi cars use tires of the 185/80R1490S type.
Tire section width and height ratio (aspect ratio) are two important indicators for describing tire size.
The tire section width refers to the maximum distance between the two outer sides of the tire after it is inflated according to regulations. It is generally divided into units of 5mm, but the section width tolerance of new tires is 63. Sectional width refers to half the difference between the outer diameter of the tire and the nominal diameter of the rim after the tire is inflated. The tire aspect ratio (H/B) is the ratio of the tire section height H to the section width B, expressed as a fraction after the diameter is rounded. Generally it is a multiple of 54. For example, car radial tires are divided into 60, 65, 70, 75 and 80 series. The graph below shows the maximum driving speed for different tire constructions.
Maximum driving speed of tires with different nominal diameters in tire structure speed level (hm/h)
10 12 /13
120 135 150
Radial tire Q 135 145 160
Radial tire S 150 165 180
Radial tire H - 595 210
Foreign tire specifications are diversified, and my country’s tire Specification marks are mainly divided into imperial and metric specification marks.
Imperial specification mark:
Generally, this mark is used for ordinary section truck tires and bias ply tires for cars. It is mainly expressed as the following part.
A Nominal section width of tire, unit is in
B Tire structure mark
C Nominal diameter of rim, unit is in
D Layer
The structural mark of radial tires is represented by "R", and the structural mark of bias tires is represented by "-". The ply refers to the specific strength mark of the tire withstanding the maximum load. It does not necessarily represent the actual number of ply layers. For example, a 9.00 specification 12-ply tire can have several actual ply numbers, but the maximum load is 2050kg.
For example: 6.5R 16 6P.R.
6.5: Nominal tire section width (6.5 in)
R: Radial tire mark
16: Nominal diameter of rim
6P.R.: Tire level 6 (maximum load is 635 kg, corresponding air pressure is 3.50kg)
Metric specification mark:
Generally, radial car tires use this representation, which includes the following content:
A Nominal tire section width, in mm
B Nominal tire aspect ratio
C Speed ??symbol
D Tire structure symbol
E The nominal diameter of the rim is in inches
The nominal aspect ratio of the tire refers to the tire installed on the theoretical rim The ratio of section height to section width.
For example: 195/60 H R 14
195: Nominal tire section width (195mm)
60: Nominal tire aspect ratio (H/B≈0.60 )
H: Speed ??symbol (210km/h)
R: Radial tire symbol
14: Rim nominal diameter (14in)
In order to unify the International Organization for Standardization (ISO), the new tire specification mark is composed of the following contents:
① Nominal cross-sectional width of the tire, in (mm)
② Nominal height and width of the tire Ratio
③ Tire structure mark
④ Nominal diameter of rim, unit is in
⑤ Load index
⑥ Speed ??symbol
For example, 195/60 R 14 85 H
195: Nominal tire section width (195mm)
60: Nominal tire aspect ratio (H/13≈0.60)
R: Radial tire mark
14: Nominal diameter of rim (14in)
85: Load index (515kg)
H: Speed Symbol (210km/h)
All tires for domestic cars are 185/80R 14 90S radial tubeless tires for Hongqi vehicles; 165/20R14 or 165/70 R13 radial tires for Fukang vehicles; Cherokee The tire mark is P205 (or 215, 225)/75R15, where P represents the vehicle, 205 represents the cross-sectional width (mm), 75 represents the aspect ratio, R represents the radial tire, and 15 represents the rim diameter (inch).
Tire Size
The tire size is printed on the sidewall, and there are two ways to express it, such as 34*7 or 7.50-20. The former is a high-pressure tire and the latter is a low-pressure tire. There are also many symbols, such as D for light cars, F for medium-sized cars, G for standard cars, and H, L, and J for large luxury and high-performance cars. If an R is printed on the sidewall, such as 175R13, it means that the tire is a radial tire with a width and length of 175mm (6.9 inches) and is mounted on a rim with a diameter of 13 inches (330mm). The word RADIAL is usually engraved on the wheel.