A tire (U.S. spelling) or tyre (UK spelling) is device covering the circumference of a wheel. It is an essential part of most ground vehicles and is used to dampen the oscillations caused by irregularities in the road surface, to protect the wheel from wear and tear as well as to provide a high-friction bond between the car and the road to improve acceleration and handling. Today most tires, especially those fitted to motor vehicles, are manufactured from synthetic rubber, however other materials such as steel may be used.