Dallas is 8 hours behind Riyadh
Best overlap: 4:00 PM to 6:00 PM in Riyadh is 8:00 AM to 10:00 AM in Dallas.
Riyadh and Dallas overlap from 4:00 PM to 6:00 PM (Riyadh) to the equivalent 8:00 AM to 10:00 AM in Dallas — that's your meeting window. The shared window is only 2 hours — treat 4:00 PM in Riyadh (8:00 AM in Dallas) as the one fixed point and plan everything else around it. Bear in mind Dallas shifts for daylight saving while Riyadh stays fixed — recheck these hours after each clock change.