If you don't want to get any M4R MP3 file converter downloaded and have a high-speed internet connection, free online conversion service is another method. You'll find a plenty of online MP3 M4R converter service once you google related keywords. However, there are some common defects and limitations of those tools which you need know.
1. Some sites allow you to convert M4R files but you can only upload limited amount of files and the size of each file has been restricted as well.
2. There are few output formats for selection and some websites even can’t recognize M4R.
3. Poor output quality is a common defect of online converter.
4. I believe most people have the experience that you have to wait for a long time before the conversion finished with a good fast net connection. Let alone poor net condition.
Take all into consideration. It’s advisable to convert M4R to ringtone with the first solution via Free HD Video Converter. Besides M4R MP3 conversion, Free HD Video converter also provides the best method of making iPhone and android ringtone. I think you’ll totally surprised by its performance.