How to read a tyre?
If you want to know more about your tyres, you need to decode what is written on its side. Check your car manual to know which type of tyres are compatible with your car. You can also use our tyre selector by car model.
What are the codes on the side of my tyres?
The first code indicates the size of the tyre and the second indicates the load and speed that it can operate up to.
235/55 R17 99W
(width/height/diameter/load index/speed index)
1) Tyre Width (235)
The number 235 indicates the width in millimeters. For standard tyres, this number varies between 125 and 335 millimeters.
2) Section Height (55)
55 is the height of the tyre section, expressed as a percentage of the width. In this example, the height is 55% of the total width of 235 mm, which is 129,25 mm.
The letter R stands for Radial, the type of tyre. You may also see ZR indicating the tyre is for high speeds or RF which indicates that it is a Run-Flat tyre. Although the majority of tyres are now Radial type, a bias, or cross-ply, construction tyre will have a “-“ in this position.
3) Diameter (17)
17 is the diameter of the tyre’s inner rim. It is always expressed in inches. The number varies between 10 and 23 inches for passenger vehicles.
4) Load Index (99)
99 is an index of the maximum load carrying capacity per tyre at the speed designated by the speed symbol (99 = 775 kg).
|Load Index||Kg||Load Index||Kg||Load Index||Kg|
5) Speed Index (W)
The last letter indicates the maximum speed for the tyre at full load. W corresponds to a maximum speed of 270 km/h. This should generally be higher than your vehicle’s maximum speed. However, there are exceptions for winter tyres and exemptions in some countries. Be careful not to have tyres with a lower speed rating or load capacity (see above). Your car’s manual will provide more detail.