Tire tracks can also be especially useful. Every tire has on easy-to-see tread, a pattern of the lines in the rubber. Even without specialequipment, police can often see this pattern in mud, on grass, or even on the surface of a hard road near a crime scene. A case in the state of Minnesota is a good example. The police tried for four years to find a criminal who had set several fires. Then they found and old tire track, obviously from a truck, at the edge of burned-out forest. An officer took a picture and tried to match the tread pattern to the tires of trucks he saw around town. Finally, he found a perfect match, and the truck’s owner confessed to starting the fires.