When air is pumped into a cycle tyre the volume and pressure of the air in the tyre, both are increased. What about Boyle’s law in this case?
The volume of a gas is inversely proportional to the pressure of the gas at a constant temperature as stated by Boyle’s law. When air is continuously pumped inside the tyre, the number of moles of gas (i.e. the mass of the gas) increases. Since Boyle’s law is only applicable for a constant mass of gas, it will not hold true in this case.