To measure the wear on your city bike tyres and to know when they need replacing, you need to inspect the tread. Usual signs of wear include: - tread starting to fray - the appearance of a series of micro cracks - low tread depth - the carcass becomes visible. In all these cases the tyre is worn and needs replacing.

To remove your tyre, deflate the inner tube until no more air comes out. Once deflated, use a tyre lever to remove the tyre from the rim.

To put the tyre back on, place one side of the tyre into the bottom of the rim. Next, inflate your inner tube to approximately 30% before putting it into the tyre (inflating it beforehand reduces the risk of pinching the inner tube). Then, insert the other side of the tyre into the rim, starting on the side opposite the valve. Before inflating the inner tube all the way, check to make sure it isn't pinched between the tyre and the rim.

Inflate your tyre carefully. The recommended pressure is indicated on the side of your tyre. Also, before each outing, make sure that your tyres are at the correct pressure for your ride.

When inflating your tyre, make sure you inflate it to the suitable pressure for the terrain you will be riding on and, above all, the weather conditions you will be riding in. When riding in rainy weather, lower the tyre pressure to increase the tyre's traction. On the other hand, when riding in dry weather, you can increase the pressure for better performance.