Tom and his wife has an iPhone 6 Plus, and she wants to transfer an old ringtone from her iPhone 5 to her new iPhone. Leo says they should be sure to have the latest version of iOS because there was a bug that deleted ring tones that was fixed recently. They'll need iOS 8.1.2.
Import the ringtone into iTunes, and then they can sync it back to the iPhone 6. Tom and his wife can also create their own ringtones through iTunes, and they can find out how to do that here (digitaltrends.com). There's also an OS X app called RingTones that will also create it.