As a result of certain weather conditions, Typhoon Tip quickly strengthened in the open waters of the western Pacific Ocean. Late on October 10, the typhoon reached Category 4 strength on the Saffir-Simpson Hurricane Scale, and the next day it became a "super typhoon". 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 typhoon continued to gain strength, and early on October 12, Reconnaissance Aircraft recorded a worldwide record-low pressure of 870 mbar (hPa, 25.69 inHg). The typhoon had winds of 305 km/h (190 mph) while located about 840 km (520 mi) west-northwest of Guam. At the time, the typhoon's eye was only 15 km (9.3 mi) wide.