Convert RAR to WAVE

You cannot convert WinRAR Compressed Archives directly to WAVE Audio Files (.rar to .wave conversion); certainly not in the proper conversion sense.

You could, however, extract existing audio data files, such as WAV, but only if your RAR archive actually contains such audio files. Certain dedicated tools, like for instance WinRAR or 7-Zip, allow users to explore the contents of RAR archives, and if needed, extract any audio data files.

Simply put, it is impossible to convert RAR to WAVE directly.
Thus, there is no so-called rar to wave converter or a free online .rar to .wave converter to be found.