The sidewall of a tyre can look like a meaningless set of numbers, letters and symbols to a layman. One might even think they’re mere decorations. Hidden among these is useful information about the tyre’s construction, size and type that one needs to know before buying. Here are a few guidelines on what your tyre markings mean
- Cross Section width(mm)
The first three numbers, in this case 235, refer to the section width of the tyre. This is the measurement, in millimeters, from the tyre’s inner sidewall to its outer sidewall.
- Aspect ratio (%)
The aspect ratio, or profile, refers to the height of the sidewall as a % of the section width. In our example, 45 means the height is equal to 45% of the 235mm width. The bigger the aspect ratio, the bigger the sidewall will be.
- Radial construction
The letter R means the tyre is a radial construction. Almost all new car tyres are radials.
- Rim diameter(inch)
The number to the right of the construction type is the rim diameter, measured in inches. In this case, it’s a 17” wheel.
- Load index
The load index is the maximum load (in kg) that the tyre can carry. The capacity of each tire in withstanding the load is referred to as the load capacity. The load index is a numerical code associated with the maximum load a tire can support.
- Speed symbol
The speed symbol, in this case W, indicates the maximum speed at which the tire can carry a load corresponding to its Load Index under service conditions specified by the tire manufacturer. Below is a table with corresponding speed symbols.
| Speed Symbol | Speed Km/h | Speed Symbol | Speed Km/h |
| N | 140 | U | 200 |
| P | 150 | H | 210 |
| Q | 16 | V | 240 |
| R | 170 | ZR | 240+ |
| S | 180 | W | 270 |
| I | 190 | Y | 300 |
As we can see from the information above, knowing the meaning of the markings on your tyres doesn’t only ensure you buy the right tyres but also helps you know how to best take care of the tyres. If you’re not sure of the
The last four numbers relate to the date of manufacture, so you can identify the age of your tyre. In this example, the date code is 1017 which would mean that the tyre was manufactured in the 10th week of 2017. European ECE Type Approval This indicates that the tyre has been tested and passed European safety standards.
There is no obligation to use them in Europe, and the values are determined in the conditions of North America. As you can see, every tyre has a number of markings that indicate different features and parameters.