Internal separation happens between tire components at tread area. Part of tread rubber and / or fabrics are lost and internal construction is exposed.
Separation of the tread or fabric is caused by overloading, cuts, abnormal heat built-up, etc.
A tire with tread or fabric separation must be removed immediately and be checked by the tire manufacturer. If tread separation is serious, part of most of the tread (often including the reinforcing fabric in bias tires) may peel off, which in turn may lead to damage to the aircraft. Therefore, remove the tire immediately.
Early signs of tread separation can manifest themselves in the form of a tread bulge, local uneven wear (depression) or a local tread/sidewall rubber split. Remove the tire immediately.
If the tire is still inflated after aircraft is at parking position, record the pressure after it has cooled down (allow 3 hours). Then deflate the tire before removing the wheel assembly.