Reuse Of Tubes
A new tube should be used when installing a new tire. Tubes grow in service, taking a permanent set of about 25% larger than the original size. This makes a used tube too large to use in a new tire, which could cause a wrinkle and lead to tube failure.
Source: Goodyear Tire Care & Maintenance Guide 09/98
Used Aircraft Tubes
Aircraft tubes are made of natural rubber and are made slightly undersize, so they will fit easily into a new tire. Aircraft-tire plies are made of nylon, and will "grow" slightly in service. The tube will also grow, and will eventually take a permanent set to the (now) larger inside-tire dimension. If this now-larger tube is later put into a new tire, it may be too large for the inside-tire cavity, with the result that the tube may have folds in it. In service, these folds may eventually wear through and destroy the tube's ability to hold air. A slow wearing through will result in a slow leakage of air, and the pilot will be alerted to the problem before it becomes too serious. However, if the tube is torn in a particular takeoff, the tire will probably go flat in mid-air, without the pilot having realized what is wrong. Considering the risks in reinstalling a used innertube, we recommend a new tube installed in a new tire.
Source: Specialty Tire Product Guide