I am amazed that there is this problem over tyres, not being involved with preservation now. I had dealings with an Indian company in Bombay a few years ago and they were interested in selling worldwide any tools, filters, whatever, that would sell. I sent them loads of catalogues and brochures for everything from shock absorbers to oil filters.
I have to say that this company looks impressive with their range of tyres...you Aussies have always been able to supply new manufactured parts for old vehicles..pistons and liners come to mind as there is a company that advertises in RESTORED CARS for whom I write.
http://www.antiquetyres.com.au/index2.html