Builtin Sound file, Between the Wheels


I have updated, and uploaded the Alcaron UFOs that some of them need to be completely silent track sounds.
I have managed to use a silent Track, and no engine sounds. All in all they are silent.
But there is still an issue of hearing a kind of smooth rolling sound that I found in the builtin in folder kuid 570470 100003 (in_between_wheel.wav)
I silenced that sound with audacity as a test to see if it would now be silent when driving the UFO, The (in_between_wheel.wav) sound is still persistent.
Where is that sound file coming from, and how do I Silence it?

Any help would much be appreciated
Kind regards.