As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DECLARED EMERGENCY INTO JFK DUE TO A SUSPECTED RIGHT MLG TIRE TREAD SEPARATION AFTER A REPORT OF DEBRIS IDENTIFIED IN SJU. INSPECTION CONFIRMED TREAD SEPARATION ON THE NR 4 TIRE WITH NO LOSS OF PRESSURE. REPLACED NR 3 AND 4 MLG TIRES. (LP 8534978, 8534980 - AIRCRAFT WAS GROUNDED)