A lot of iPhone users have problem syncing iPhone ringtones. Some questions are like "I can't sync ringtone to iPhone", "unable to sync ringtone to iPhone" and so on. Some are more detailed, such as:"it shows up as a ringtone in iTunes, but it won't sync to the phone. I've restarted my phone several times, hoping that would do it. I've removed all my ringtones, then re-synced them...but still nothing.", "I have ringtones in ringtone folder yes have changed to m4r, can play ringtones on pc and all are under 30 seconds long, have tried syncing ringtones but can only manage to get one on my phone."
Below are some tips for you if you have the similar problems.
First, make sure that:
Ringtones play in iTunes
All the ringtones are under 30 seconds
They show up under the ringtones tab
They are in the ringtone section of iTunes under library
Second, If the ringtone is in iTunes and not appearing on your iPhone after a successful sync, make sure that none of the song fields (song name, artist, composer, etc) have special characters (like quotes, for example iPhone-Ringtone the"-" will cause the syncing problem).
Third, The Length of your ringtone. Although they show up in the ringtones on your iPhone in iTunes after successfully syncing to your iPhone, they will not appear in the custom ringtones section on your iPhone if they are longer than 30 seconds.