I’d be pretty surprised if there were a program that could do it, b/c Real files are streaming media format - it isn’t stored anywhere, it plays in real time. The conversion program would have to basically “record” the stream while it played, (which would open a can of worms fidelity-wise, ex: it would not sound any better than the way it sounds while playing on your system), store that data dynamically somewhere, (which would create a very large temp file), then write it to WAV format when finished. (which would create a WAV even larger than the temp file).
Did you ever used to record songs off the radio by holding your mic from a portable tape player up to the radio speaker? It would be kinda like that, except ambient traffic could easily cause the song playing on the radio to stutter, reacquire, etc while you were recording it.