I first found out about this at Macrumors

Ringtone criteria

• file extension is m4r i.e songname.m4r


• time length short ( under 30 sec)

Import audio to Itunes

Import your song to itunes to convert the file type to m4a. i.e. songname.m4a

Crop it down to under 30 seconds

If the song or audio is over 30 seconds then you will then to crop it.

1. right click song


2. select Get Info


3. go to Options tab


4. change Start time and End time to suit (total under 30 sec)


5. click OK

6. Then right click on the song and select Convert Selection to ACC

Change the Extension

1. Find the cropped m4a file in your itunes folder. ( this will be in your music for windows users)


2. Rename the extension to m4r

Import back to Itunes

1. Double click or right click to select open with ..itunes

The audio should then appear in the ringtones section

Sync

1. Sync the iphone with itunes


2. On Iphone go to Setings > Sounds > Ringtone

The Added ringtone will now be listed under Custom