1. Open iTunes and check is your iPhone connected to your computer/laptop.
2. Click on DEVICES -> APPS -> go to FILE SHARING -> highlight the tones you wish to sync -> click on the SAVE TO button at the bottom and save this, for easy access, to a file (give it title as My Ringtones) on your desktop.
3. Go back to LIBRARY -> and drag your tones, from your desktop file, to the (bell icon) TONES (this took the place of the RINGTONES tab under DEVICES -> APPS, if you are not showing this icon then go to EDIT -> PREFERENCES -> GENERAL tab and make sure that the TONES box is checked).
4. Click on the arrow just left of the name of your device. You will see a list of folders.
5. Drag your ringtones to the (bell icon) TONES.
6. Check on your iPhone -> Settings -> Sounds and the new ringtones should be at the top.
7. Choose the ringtone and activate.
Must Things:
Keep the ringtone into the TONES folder.
Ringtone must be below 30 seconds length.
Dont forget to convert the file .M4R file before syncing to iphone(i.e., Ringtone is iphone is of .M4R format)