With most standard tires that have symmetrical tread patterns, it does not matter which way the tire is fitted on the rim or in which position it's fitted on the car. However, some tire manufacturers produce tires with specific "directions of rotation" in order to improve their wet grip and minimize noise generation. The direction of rotation is marked on the side of the tire with an arrow. For optimum performance, that side of the tire must be visible when installed, and the tire must roll forward in the direction of the arrow.