Why does a car tyre expand in hot weather?

A car tyre expands in hot weather due to the increase in air pressure inside the tyre caused by heat.

In more detail, this phenomenon can be explained by the ideal gas law, which states that the pressure of a gas is directly proportional to its temperature, provided the volume and the amount of gas remain constant. This law is often expressed as PV=nRT, where P is pressure, V is volume, n is the number of moles of gas, R is the gas constant, and T is temperature.

When the weather is hot, the air inside the tyre heats up. According to the ideal gas law, as the temperature (T) increases, the pressure (P) inside the tyre also increases, assuming the volume (V) and the amount of gas (n) remain constant. This increase in pressure causes the tyre to expand.

It's important to note that this expansion is not necessarily a good thing. Overinflation can lead to a rougher ride and increased wear on the tyre. It can also increase the risk of a blowout, especially if the tyre is already worn or damaged. That's why it's recommended to check your tyre pressure regularly, especially in hot weather, and to adjust it as necessary to maintain the manufacturer's recommended pressure.

In summary, the expansion of a car tyre in hot weather is a direct result of the ideal gas law. The increase in temperature causes an increase in pressure, which in turn causes the tyre to expand. This is a clear example of how fundamental principles of chemistry are at work in everyday life.