A WAV file will be significantly larger than its mp3 counterpart. It seems somewhat odd that you'd be able to use WAV files and not mp3s as ringtones. :thinking:

Winamp will convert mp3's into wav file by using the diskwriter plugin as the default output in the preferences. But as I said you'll be hard pressed to fit a 50mb+ wav file as a ringtone. As someone suggested above you'll need Sonic Foundry (or a similar wav/audio editing application) to cut out the part you want for your ringtone.