How dumb am I? It could have been possible to source a tyre in Mildura, and have a competent tyre fitter waiting for Jeff's arrival on his return journey tomorrow. Sorry Jeff, I didn't think of the issue further last night. There is a competent mechanic in the Port Augusta region, if a tyre could have been sourced today.
Edit:
Just checked the tracker, as he is on his return east, did he get a front tyre?
I'll ring around just in case.