An inner tube is a type of rubber tube that is used for a variety of purposes. It is most commonly used as a tire inner tube, which is an inflatable tube that fits inside a bicycle or vehicle tire to provide a cushion between the tire and the wheel rim. It can also be used in medical applications, such as a VEIN graft, where it is used to replace a damaged VEIN. In addition, it is sometimes used as a replacement for the AORTA, which is the main artery in the body.