Tehran is 6 hours behind Adelaide
Best overlap: 2:00 PM to 6:00 PM in Adelaide is 8:00 AM to 12:00 PM in Tehran.
Keep meetings inside 2:00 PM to 6:00 PM in Adelaide — that maps to 8:00 AM to 12:00 PM in Tehran. Tehran is 6 hours behind Adelaide, leaving about 4 hours of daily overlap — enough for most meetings if you don't leave them too late in the day. These times hold for most of the year, but Adelaide's daylight saving (which Tehran doesn't use) shifts them by an hour twice annually.