For anyone chasing new tyres for the Nationals I suggest you get in contact with Craig Hornibrook from Hornibrook Motorsport at Geebung in Brisbane.
Hornibrook Motorsport - Brisbane's Premier Motor Sport Tyre Dealer!
On the Hoosier DOT Tyre he's cheaper than MDMsport and Tirerack USA and his service is excellent.
For the last few years I've always bought my tyres from him and I've again just done the sums and found again his pricing is still very very good.
Spookypt