Tire fires, where tires are stored, dumped, or processed, exist in two forms: as fast-burning events, leading to almost immediate loss of control, and as slow-burning pyrolysis which can continue for over a decade. They are noted for being difficult to extinguish. Such fires produce much smoke, which carries toxic chemicals from the breakdown of synthetic rubber compounds while burning.
Tire fires are normally the result of arson or improper manipulation with open fire. Tires are not prone to self-ignition as a tire must be heated to at least 400 °C (750 °F) for a period of several minutes prior to ignition.
Extinguishing tire fires is difficult. The fire releases a dark, thick smoke that contains cyanide, carbon monoxide, sulfur dioxide, and products of butadiene and styrene. Burning tires are heated, and, as they have a low thermal conductivity, they are difficult to cool down. Moreover, they frequently burn inside even if they are extinguished from outside, and easily reignite when hot. One possible remedy is to cover the fire with soil, reducing the supply of oxygen and the exhaust of smoke. After extinguishing and cooling down (which may last several days), toxic chemicals can be neutralized.
In Northern Europe new and used tires are stored in large warehouses also known as tire hotels. Fire is a growing concern, and as tire fires are difficult to extinguish regular sprinkler systems are not sufficient. Inert gas extinguishing systems like INERGEN in combination with an effective detection system would be the preferred choice for protecting these warehouses. Tests for establishing the minimum design concentration (MDC) are currently being performed in Denmark.
Some notable tire fires include: