The central pressure dropped 92 mbar ( hPa , 2.71 inHg ) from October 9 to 11 . During this time , the typhoon became extremely large , reaching a record diameter of 2,220 km ( 1,380 mi ) . The central pressure dropped 92 mbar ( hPa , 2.71 inHg ) from October 9 to 11 , during which the circulation pattern of Typhoon Tip increased to a record diameter of 2,220 km ( 1,380 mi ) .