Standard motorcycle tires are built according to the standardization of the manufacturer. However, some bikers oftenly modify their tires to the bigger or smaller size. Even though bigger tires could beutify the look of the motorcycle, the tires could also bring you some negative effects such as damaging your motorcycle parts (chain and gear) and decreasing the acceleration. On the contrary, changing your tires to smaller size would reduce your top speed and reduce the grip of the tires which makes it accident-prone. But, in a positive way, smaller tires could increase the acceleration of the motorcycle.
