What do all the markings on a car tire mean?
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We all know that tires are an important part of our vehicles. Keeping them in good condition can help prevent blowouts, poor road holding and even reduce fuel consumption. In case you need to replace them, it is important to know how old the tires on your vehicle are as well as their size. There is a lot of information on the sidewall of your tires. We will take a look at what they are and what they mean.
Check the age of your tires by looking at the numbers embossed on the sidewall of the tire. The first two digits show the week, and the second two digits show the year the tire was made. This allows you to determine the age of the tire. Even if the tire doesn’t look worn, it should be replaced at least every 10 years (however, some automotive specialists recommend replacing tires more often, even every 4 to 5 years). After this time, the tires can be damaged much more easily and the road holding will be greatly reduced. Make sure you have checked all 4 tires and the spare.
Suppose that the sequence of letters and numbers on the sidewall of your tire is 225/45 R18 95H. What does this actually mean?
Width of the tire
The number that usually appears first, in this case “225”, refers to the width of the tire in millimetres. It is measured from sidewall to sidewall. This is one of the numbers you need to know when buying new tires.
The next number, “45” in our example, is the aspect ratio of the tire. This is the rim height measured as a percentage of the tire width. In this case, 45 means the height of the tire is 45 percent of the width of the tire.
The next marking is a letter which refers to the internal construction of the tire. “R” in the example above represents the radial structure. Other types include “D” which indicates a diagonal or “B” which stands for bias-belted construction. Most of the tires used on vehicles today are of a radial construction. Radial means that the internal cords of the tire are arranged in a radial direction.
Diameter of the rim
Another important marking is the next one on the list. The number “18” in the example above is the diameter of the wheel rim in inches.
The number after the rim size is the load index. In our example, the load index is “95”. This is a code associated with the maximum load that a tire can support when properly inflated. For most cars, the tire load index ranges from 75 to 105. The numbers refer to a specific load-carrying capacity. To see what the maximum load capacity of your tires is, check the load index table, which you can easily find on most automotive websites.
The next character in our example is another letter. It refers to the speed rating of the tire. Tires can have any letter from A to Z here. Each letter coincides to the maximum speed a tire can sustain under its recommended load capacity. Even if you have high-performance tires that handle high speeds, it is recommended to always stick to the speed limits.
Other markings on the tires
There are also other markings on the tires that may have some relevance. These are just examples of other markings you can expect to see on your tires:
— SSR denotes a self-supporting run-flat tire;
— MOE refers to Mercedes-Benz Original Extended tires;
— M+S means that the tires are suitable for use in mud and snow;
— DOT refers to compliance with vehicle safety standards of the local authorities;
— 36/19 are the last numbers here and refer to the week and year of manufacture, as mentioned earlier.
While these markings may differ depending on the country where the tires are made, most of these markings are standard around the world. If there are markings on your tires that are not listed, ask your supplier for information to ensure you understand all the information correctly.