is it possible to convert m4r files to mp3

Hi all

Up until recently i owned an iPhone 4.

I have purchased a few m4r ringtones from the iTunes store and want to convert them to mp3 to use on a different phone.

is this possible to convert?

I have been able to convert purchased m4a files natively within iTunes to mp3 no problem.

i have tried changing the file extension to m4a but iTunes still sees it as a ringtone so doesnt give me the option to convert to mp3

any ideas?

Thanks