Dallas is 1 hour behind Philadelphia
Best overlap: 9:00 AM to 6:00 PM in Philadelphia is 8:00 AM to 5:00 PM in Dallas.
Philadelphia and Dallas overlap from 9:00 AM to 6:00 PM (Philadelphia) to the equivalent 8:00 AM to 5:00 PM in Dallas — that's your meeting window. You won't be short on options — 9 hours of overlap leaves space for recurring syncs and ad-hoc calls alike.