Quite deep rubber wearing happens at singular location of tire.
Skid burns result from brake malfunctions or locking of the wheel, most often during landing.
If the spot wear reaches the reinforcing fabric (bias) or aramid cord protector (radial), remove the tire from the aircraft.
If the spot wear does not reach the reinforcing fabric (bias) or aramid cord protector (radial), if there is sufficient groove depth in the whole spot wear area, if there is not incipient separation and if vibration is not detected while rolling, leave the tire on the aircraft.