Tyres are probably one of the most important parts of a bike and why not? They are the only point of contact between the machine and the tarmac. If tyres are not good enough, it really doesn’t matter how powerful the engine is or how brilliant the chassis is, neither will the bike go as fast as it is supposed to go nor will it handle any better. So at the end of the game, tyres play a vital role when it comes to delivering the best performance out of a bike or a car. Hence, there is a whole science behind the making of a tyre and sometimes tyre makers spend a fortune trying to get the things right or to up come up with a product which meets the global standards.
There are various types of tyres present in the market today, and they come in all shapes and sizes. But have you ever wondered what does the numbers written on the tyre sidewalls mean? Well, it is extremely important to know what specific type of tyre your motorcycle rolls on, and reading the sidewall markings is going to tell you exactly the same. So read out our thorough report below to enhance your tyre knowledge and to learn the meaning of the tyre sidewall markings.
Format of the tyre markings:
All the tyres come along with the standard information which appears in this format as example 120/70 ZR17 M/C (58W), apart from this information some tyres are tagged with the specific ‘XYZ’ tyre model name and the company name which has manufactured the tyre.
Width of the tyre:
The number which appears first in the code denominates the tyre width. For example in the code ‘120/70 ZR17 M/C (58W)’, 120 is the tyre width and it is always measured in millimeters or ‘mm’ from sidewall to sidewall. The width of the tyre is a major factor in determining the handling and turning characteristics of a bike. The bigger the width of the tyre is, the more surface area it will cover, hence greater grip. At the same time, a fatter tyre makes for a motorcycle which is comparatively harder to turn in and this is one of the reasons why cruisers with fat rear tyres are lazy to turn into a corner.
Aspect Ration or Height:
The following numbers in the code ‘70’ denote the aspect ratio of a tyre, or it is sometimes also referred to as height. The number which is present in the code, unlike width is not expressed in ‘mm’ but as a percentage figure of its width. In simple details, in this case, the aspect ratio is 70% of the 120mm width, making it 84mm.
Usually on a sports bike the next code digits are ‘ZR’. The Z denotes the speed rating of the tyre while the R simply means that is a radial type tyre. In the above code, Z denotes that this tyre is rated above 240kmph or 149mph. The following number ‘17’ signifies the diameter of the tyre in inches, and in this case the tyre is of 17inch diameter. ‘M/C’ in the code says that this is a motorcycle tyre.
Load index and speed rating:
The last bit of information on the code is ‘58W’ but you will need the chart below to decode the same. This code is very critical when buying a new tyre and it is called load and speed index of the tyre. In the present case, the number ‘58’ signifies that the motorcycle tyre can carry a maximum weight of 236kgs at maximum pressure. And the ‘W’ rating says that the tyre can do a maximum top speed of 270kmph when properly inflated and loaded. This is called the load index & speed rating of a tyre which should always be matched whenever making a new tyre purchase.