Question

Why does a cycle tube burst in summer?

Answer 1

If a gas kept in a container is heated it expands, but if the walls of the container are not flexible (i.e., the walls are rigid) then due to expansion the pressure in the wall increases. This pressure sometimes exceeds too much that the wall becomes unable to withstand and eventually cracks up.

Complete answer:
A majority of everything in this universe expands when heated (with a few exceptions), in a gas the molecules within are further apart and they are attracted to each other with a very weak force of attraction. Heat causes these molecules to move faster, (heat energy is converted to kinetic energy) this decreases the force of attraction within the molecules and volume of a gas increases.

When the wall of the container in which the gas is heated is rigid the pressure increases as more and more gas molecules collide with the wall with an increased velocity. Now when the tyre is kept out in the summer, due to the heat and rise in the temperature the volume of the gas increases and thus the pressure inside the tube increases. A time comes when the pressure inside increases so much that the tube of the tyre cannot handle the excess pressure and it bursts out.

Note: Nowadays the tube of the tyre is made up from a bit semi-rigid material like an extra elastic rubber, so that it can handle the excess increase in pressure for quite a bit longer. Sometimes even a few volumes of gas is knowingly made to leak out of the tube in order to compensate for the expansion which is caused due to the heat of summer, this method can also protect the tyre from bursting.