As the aircraft became airborne at Adelaide Airport, air traffic controllers observed a tread separating from a main landing gear tyre. The pilot was advised and confirmed an abnormal landing gear indication. Most of the tread of a maingear tyre was found on the runway and emergency services were placed on full alert. The aircraft was operated clear of the circuit to reduce landing weight and to allow emergency services to be made ready. Later, after an inspection fly-past was carried out, the aircraft landed safely. There have been other tread losses from the same type of retreaded tyre. As a result, the operator has reduced the number of times this type of tyre will be retreaded and has also stopped the purchase of this type of tyre.