What are the main fire risks associated with tyres? How can they be prevented? What are the emergency measures to be taken? Read on to learn more.
- Under normal conditions of use and storage, tyres do not present any particular danger.
- Tyres do not ignite easily. Strong ignition source is required to initiate the combustion reaction (see flammability parameters in appendix).
- Tyres burn releasing intense heat and dense black fumes containing products such as carbon oxides, hydrocarbons (especially polycyclic aromatic hydrocarbons), nitrogen oxides, halogenated acids and large quantities of soot and unburned material. In some cases, tyres burn releasing oily liquids.
- Composition of fire smoke varies depending on the oxygen supply to the fire (open air or confined space fire, under-ventilated or over-ventilated) or on the weather conditions (wind, fog, rain, outside temperature, ...),
- The amount of smoke produced by tyres can quickly compromise visibility. In confined spaces (such as subway tunnels, platforms and underground stations for example), they can also compromise the viability of the atmosphere.
- The Michelin Acoustic® technology contants a polyurethane foam strip inside the tyre to reduce rolling noise radiation. This foam leads to a particular fire behavior. Acoustic tyres can burn faster than standard tyres and release very large quantities of smoke (one kilogram of polyurethane foam is likely to release in the worst case more than two thousand cubic meters of cloudy, toxic and flammable smoke at around 300°C).
Flammability parameters of a tyre under laboratory conditions
- Flash point: 288 °C
- Auto-ignition temperature: 315 °C
- Heat value: between 24 and 30 MJ/kg depending on the tyre range and composition
How can tyre fires be prevented?
- Tyres must be stored in a stable manner, in cool, dry, ventilated premises, far from open flames and heat sources. In particular, hot work processes (welding, grinding, cutting, etc.) must not be carried out in the immediate vicinity of the tyres without suitable safety devices. Direct contact with hot surfaces (including heating pipes or radiators) must be avoided.
- No smoking around the tyre storage.
- Tyres should be kept away from most chemicals, including solvents, petroleum, diesel fuel, oils, greases, acids and disinfectants.
- The reaction tyres have to fire, and of Michelin® Acoustic tyres in particular (rapid fire propagation, release of large quantities of smoke), makes it necessary to ensure that all means of evacuating personnel from storage areas are available. Regular evacuation drills are recommended.
- Tyres storage in the basement is not recommended.
- In the case of Michelin® Acoustic tyres, storage in the basement or on the first floor is to be avoided. It is the same for storage on the ground floor if the building includes floors or basement likely to be invaded by smoke.
- Tyres must be used under the conditions for which they are designed. Hot works on the wheel or around a pressurized tyre have led to serious accidents. An increase in temperature leads to an increase in pressure inside the tyre, which can cause the tyre to burst. Tyres must be kept as far away as possible from heat sources.
Emergency response in case of fire
- The main extinguishing agents are water in large quantities and foam. At the beginning of the intervention, powder can be used to suppress flames before continuing with water or possibly foam.
- The cooling of an inflated tyre that has heated up can cause the tyre to burst do to thermal shock and so must be done at a reasonable distance (5 to 10 m at least), to avoid any impact from shards and the pressure wave. Please note that in case of a mining tyre fire, specific safety protocols must be followed. Please refer to the specific technical brochure.
- A tyre heated up by flames accumulates a lot of heat. It is then very likely to re-ignition. Burnt tyres that have been extinguished must be monitored for several hours and cooled continuously. The absence of flames does not mean that the fire is out.
- Self-contained breathing apparatus must be worn when responding to a tyre fire.
Exposure to combustion smoke should be avoided.
This document is an information on the hazards of tyres under their expected conditions of use. This information is based on the knowledge available at the time of writing. It concerns the main types of tyres: passenger, light truck, truck, two-wheel, agricultural, aircraft, earth mover or mining, racing and subway tires, as well as Michelin® Acoustic tires. Supplement precautions may be recommended in the technical brochures depending on the tyre range and usage (eg. Mining tyres).
Creation date: November 2022