You’re thinking about changing your tires, but you’re having trouble navigating the combination of numbers and letters you see on your tires. However, a small mistake can cost you dearly. So how do you read a tire? We will try to answer them here.
Read a tire
You’ve found a tire that fits your budget and you’re thinking of trading in your old ones for these new ones. When you change your tire, it is very important to know its characteristics.
To better explain, let’s take as an example a tire that says 225/55R17 97W.
- Here, the 225 indicates the width of the tire. Remember that this measurement is expressed in millimeters. We can therefore say that this tire is 225 cm wide.
- The 55 indicates the height of the sidewall in relation to the width of the tire. Here, the sidewall height is 55% of the tire width. It should be noted that the higher the sidewall, the less grip the tire will have when cornering. But the ride is more comfortable.
- As for the R, it indicates the structure of the tire. Here the R stands for Radial, which is the most used nowadays. Remember that there are three tire structures: the Radial, the diagonal structure expressed in D which is gradually disappearing from the market, and the B structure or Bias Belted.
- The 17 indicates the surface of the inside of the tire. In other words, it is the size of the rim. It is usually expressed in inches.
- The 97 is the load index, which is the load the tire can support when inflated to the safe limit. Please note that a load index of 97 does not mean that the tire can only support 97kgs. In fact, we have to go back to a correspondence table. According to this table, the index 97 is equivalent to a load of 730kgs. In general, you may well opt for a different load index for your new tire. Be careful, however, to take a tire with a higher load index than your old tire for more safety.
- The W is an index of speed. It indicates the speed at which the tire is considered safe. These speeds are expressed with indices between A which is the lowest and Y which is the highest. In this example, the W corresponds to a speed of 270km/h. You can choose a tire with a higher speed rating than your old tire. But if you choose a lower index than the previous one, it will affect the handling of your car.
All you need to know
There are other markings used for tires.
- M+S, is a marking which means that the tire is certified “snow” according to the European standard.
- The 3PMSF or 3 Peaks Mountain Snow Flake indicates that the tire is reserved for snowy roads. Unlike the M+S tires, these tires have already been tested.