Rear tire scooter K66 of the company Heidenau. Its dimensions are 140/60-14, which means it has a width of 140mm, a profile of 60, and can be mounted on a rim with a diameter of 14". The profile of the tires, which refers to the height of the tire's sidewall, is always expressed as a clean number without a unit of measurement as it is a percentage of the width. For example, a tire with a size of 100/90 has a width of 100mm and a profile of 90, which means it has a profile of 100 x 0.90 = 90mm.

The load index and speed index are two other important characteristics of tires. Specifically, the load index is the maximum load under which the tires are expected to function properly and is described by an integer that corresponds to kilograms, while the speed index is the maximum speed under which the tires are expected to function properly and is described by a letter from the English alphabet that corresponds to kilometers per hour. It should be noted that the maximum weight, to which the load index corresponds, is reported per tire.

Note: The maximum weight increases proportionally with the load index number, meaning that the larger the number, the greater the maximum operating weight of the tire. Similarly, the maximum speed increases as the letter of the speed index "increases", meaning that the speed index "J" corresponds to a lower speed than that of the "S" index.

In this case, the tire is 64S, meaning that the load index and speed index are 64 and S respectively.