To avoid any misunderstandings, clincher tyres do contain a wire, but this is only there to hold the tyre on the bicycle rim. The air for the tyre is filled into the inner tube, which is held in place by the so-called tyre liner or clincher tyre. This tube can lose air and must therefore sometimes be patched at the air outlet. There are special repair tools for this, which are glued to the tube with a type of "adhesive", the vulcanising compound. There are also self-adhesive patches to repair defective inner tubes. Both types of repair kit are available in different sizes and shapes.