The numbers on a motorcycle tire, such as 120/70ZR17, represent three types of measurements that are combined. The first number, 120, indicates the tire’s section nominal width, measured in millimeters from sidewall to sidewall.
The second number, 70, represents the tire’s aspect ratio or height expressed as a percentage of its width. In this case, the aspect ratio is 70% of the 120mm width, making it 84mm. The third number, 17, signifies the diameter of the tire in inches.
The letter(s) that follow the numbers on a motorcycle tire indicate additional information about the tire. For example, the letter Z denotes the speed rating of the tire, while the letter R means that it is a radial-type tire.
The letter M/C indicates that the tire is for a motorcycle. The last bit of information on the code is the load and speed index.
The load index indicates the maximum weight that the tire can carry, while the speed rating indicates the maximum speed that the tire can handle.
It is important to note that the actual physical width of the tire on the rim can differ from the nominal width.
Additionally, the aspect ratio is a major factor in determining the handling and turning characteristics of the tire.
Understanding these markings is critical when buying a new tire to ensure that it is the correct size and type for the motorcycle.
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