Currently, all tires are manufactured by one of the following types of tread : directional , omni-directional and asymmetric . Omnidirectional tires usually are the cost and work the same in either direction of rotation. Asymmetric tires already require care when mounting on wheels , because they have a well-defined direction of rotation. Inscriptions on the sidewalls of the tires suggest that they have internal (inside) and external (outside) side.
Incorrect installation of tires they will be directed contrary to push water from the sides into the center of the tire, increasing the risk of aquaplaning. Therefore, directional tires are very important to determine the correct direction of rotation, and accordingly to mount the tire on the disc. To point out the correct way to install the tire manufacturers draw on its sidewall large arrows, sometimes stylized, indicating the direction of rotation of the tire. Instead, large arrows can be drawn with respect to one small arrow with the inscription Rotation.
If you can not find such an arrow on the side of the bus, but you can see that it is clearly directed and has a pronounced tread pattern with grooves in the form of "Christmas trees" that will never go wrong if you install the tire so that the contact patch with the road tip "herringbone" will be directed upstream traffic. That is, spinning the tires must first touch the edge of the road "Christmas trees." Only with this method of setting the bus to work properly, allowing water drainage from the contact patch with the road, thereby increasing traffic safety and reducing the risk of aquaplaning.