Convert MP3 to M4R

Converting MP3 Audio Files directly to iPhone Ringtone Files (.mp3 to .m4r conversion) is certainly possible and can be done using a dedicated ringtone maker or (online) conversion tool.

Try using, for instance, Audacity or Xilisoft iPhone Ringtone Maker, which should allow users to easily convert MP3 to M4R.

Alternatively, you can try one of several online conversion tools, such as Zamzar.