CREATE TABLE table_25214 ("Year" CLOB, "Date" CLOB, "Driver" CLOB, "Team" CLOB, "Manufacturer" CLOB, "Laps" CLOB, "Miles  ( km ) " CLOB, "Race Time" CLOB, "Average Speed  ( mph ) " CLOB, "Report" CLOB)

When was an average speed of 81.388 mph recorded?
SELECT "Date" FROM table_25214 WHERE "Average Speed (mph)" = '81.388'
SELECT "Date" FROM "table_25214" WHERE "Average Speed (mph)" = '81.388'