I've just packed my Down Jacket, Mountain Cap, loads of fleeces etc for Australia; it's already dipping to -1 at night over in Armidale, but 4hrs South where we'll stay a couple of days when we first get over it's currently 20* during the day and 6-7* at night. Really depends where you are in relation to the coast and the mountains; when we get to Armidale, NSW we'll be on top of the range, whereas when we're in Quirindi we're lower down and sheltered by the same range (and are on the inland side of them)
On the subject of tyres, what do you recommend for a general purpose dirt road tyre? I got well with BFG KO's, so am tempted with something similar in a 32" or 33" size, on a 15 or 16" rim... the good news is that none of this is purchased so I can start with a clean sheet!