Why do tyres burst if overinflated?

Tyres burst when overinflated due to the excessive pressure exerted on the tyre walls, causing them to rupture.

When a tyre is inflated beyond its recommended pressure, the air inside the tyre exerts an increased force on the tyre walls. Tyres are designed to withstand a certain amount of pressure, but when this limit is exceeded, the structural integrity of the tyre can be compromised. The excessive pressure can cause the tyre walls to expand beyond their elastic limit, leading to a rupture or a burst.

The principle behind this is Boyle's law, which states that the pressure and volume of a gas have an inverse relationship when the temperature is held constant. In the context of a tyre, when more air is pumped into it, the volume of the tyre remains relatively constant because the tyre is a sealed container. However, the pressure inside the tyre increases significantly.

The material of the tyre, usually rubber, has an elastic limit - a point beyond which it will no longer return to its original shape when the pressure is reduced. When a tyre is overinflated, the rubber can be stretched beyond this elastic limit. This can lead to microscopic cracks forming in the tyre wall, which can grow and eventually cause the tyre to burst.

Moreover, overinflated tyres are more susceptible to damage from potholes, sharp objects, and other road hazards. The increased pressure makes the tyre rigid and less able to absorb shocks, which can lead to punctures or blowouts.

In summary, overinflating a tyre increases the pressure exerted on the tyre walls, potentially causing them to expand beyond their elastic limit and rupture. This is why it's crucial to always inflate tyres to the manufacturer's recommended pressure.