@richiekhoo > No mention of the tire company buying it out.
That really did happen in the USA - see either Wikipedia https://en.wikipedia.org/wiki/General_Motors_streetcar_conspiracy or Robert Zemeckis https://www.imdb.com/title/tt0096438/ .
I don't doubt that similar efforts happened in other countries - some company called Holden's Motor Body Builders Ltd started out in Adelaide - but I also wonder if it's possible that someone was thinking about the US situation and combined that with the decline of the Adelaide trams.
Disclaimer: I'm looking at it from 9,500+ miles away.
There is a tram museum in St Kilda. It seems to be mostly about the hardware, but in my experience, places like that also tend to accumulate documents from back in the day. It might be worth visiting, and asking if they have anything you can read through. If you bring a flatbed scanner with you and give them copies of the scans, they'll probably love you forever. :D