Tire Impressions

Abstract The society we live in today relies heavily on automobiles for transport. This leads to many wheels on the road and inevitably where a crime is committed an automobile would have some sort of involvement with the crime itself, or the criminal himself. In 2002, the world passenger car fleet hit 531 million cars, with a quarter of these cars being in the United States 1. Of these, 72% of vehicles have four tires with the same tread and design and 14% have two pairs of tires with the same tread and design. Regarding the size, 97% of all cars have four tires with the same tread size, 1.6% has two pairs and 1.4% has three the same and one of different tread size 2. In the majority of cases in which an automobile is involved, the suspect used the automobile to drive to and from the crime scene. Tires are likely to leave some sort of pattern or trace evidence at the scene of crime. Tires are manufactured using natural and synthetic rubber. The rubber is then subject to an entire process in order to manufacture a tire 3. These tires are manufactured with a particular tread pattern to ensure maximum grip and purchase between the tire and the surface of the road. Many different tread patterns exist. Elemental pattern features include waves, lines, diamonds, zigzags, curves, blocks, etc. In addition to these manufacture characteristics, acquired characteristics such as wear and tear, cuts, small holes, etc., can be often present 4. Tire marks can thus be highly informative but unfortunately they are commonly overlooked. As a result, they are often destroyed before any potential exploitation could take place 5. This article presents the examination and value of tire marks in a forensic examination.