First of all, the tires are positive and negative.

Generally, there is an "outside" sign on the outside of the tire, which is also the most common sign of the tire. If it is installed reversely, the "inside" sign will be exposed. If you see it, remember to change it back quickly.

Some tires are not marked, so professionals will distinguish them according to the numbers on the tires. For example, "3520" on the outside of the tire means that it was produced in the 35th week of the 20th year. This side is facing the outside (there is a tip: when buying a new car, remember to see if the four tires are the same production date).

Snow tires usually have production date on both sides, and there is no "outside" and other marks. In this case, it needs to be distinguished according to the arrow mark on the tire. The arrow indicates the direction in which the tire travels and rolls.

How are the tire specifications made up?

Tire specification is composed of tire section width, percentage of flat ratio, hub size, load index and service speed

For example, 215 / 60 R16 77h. Where 215 means that the tire width is 215 mm, 60 means that the flat ratio of the tire width is 60%. R16 is applicable to 16 inch hub, 77 is load specification, and H is speed grade.

Assuming that the tire size is 195 / 55 / r1685v, the following are the meanings of numbers and letters:

195 - refers to the tire width of 195mm.

55 - refers to the flat ratio of the tire, i.e. the section height is 55% of the width.

R - refers to that the tire is a radial tire (the inner layer of this tire is manufactured by radial tire).

15 - means that the rim diameter is 15 inches.

85 - load index 85 represents the maximum load-bearing capacity of 515 kg, and the four tires are 515 kg × 4 = 2060kg.

Vi V - refers to the speed level of 240 km / h.

European and American countries have different tire specifications Tire specifications are usually represented by a group of numbers. The first number represents the tire section width and the latter represents the rim diameter in inches. There are many ways to express tire specifications, and there are generally four kinds on the market, namely British system, German system, metric system and American system. Tire specifications are expressed as follows:1. The specification of the British system is adopted by the former vassal countries of Britain, and the unit is inches.2. The German specification is similar to the "metric system". In addition to the tire width expressed in mm, the flat ratio of the tire is also increased. The inner diameter of the tire is still in inches, followed by the load index and speed mark.3. The first letter of American system indicates the applicable vehicle type of the tire, the second letter indicates the width of the tire, the third word indicates the flat rate, the fourth letter is the speed mark, and the last is the diameter suitable for the steel ring.

European and American countries have different tire specifications

Tire specifications are usually represented by a group of numbers. The first number represents the tire section width and the latter represents the rim diameter in inches. There are many ways to express tire specifications, and there are generally four kinds on the market, namely British system, German system, metric system and American system. Tire specifications are expressed as follows:

1. The specification of the British system is adopted by the former vassal countries of Britain, and the unit is inches.

2. The German specification is similar to the "metric system". In addition to the tire width expressed in mm, the flat ratio of the tire is also increased. The inner diameter of the tire is still in inches, followed by the load index and speed mark.

3. The first letter of American system indicates the applicable vehicle type of the tire, the second letter indicates the width of the tire, the third word indicates the flat rate, the fourth letter is the speed mark, and the last is the diameter suitable for the steel ring. 

The international standard tire specifications are in millimeters, and each mark indicates the tire width, flat ratio, tire type, rim diameter, load index and speed level respectively. Here is how to check the tire size:

1. For example: tire specification 205 / 55r1691w, 205 indicates that the width of the tire is 205mm, and 55 indicates that the percentage of section height and width of the tire is 55%, that is, the flat ratio of the tire.

2. "R" stands for the word radial, which means radial tire, 16 means the rim diameter is 16 inches, 91 means the load index, and W means the allowable speed level of the tire.

3. Tire type identification: common indications include "X" high-pressure tire, "R", "Z" radial tire and "I" low-pressure tire.