There are quite a few threads on tyres, if you read through them, you may not be any wiser. Tyre wear / longevity seems to vary a great deal and will depend on a range of things, for example (but not necessarily limited to):
- Mass - rider and luggage
- Speed
- Throttle exhuberance
- Road surface
- Tyre pressure
- Make / model of the tyres
Some riders (me) get poor life out of a set of tyres (as low as 10,000km), others (Biggles) get extraordinary life (25,000km) - Bill will be along soon to correct me if I'm wrong.
Some laps riders have a set of tyres ordered and waiting for them at places like Darwin, Brisbane, Townsville or Perth (you get the idea). Otherwise, if a tyre is needed in a remote area, a five day (or more) wait in an outback town might spoil the trip.
Once you get an itinerary, share it, there'll be a few members that will join you on a leg or two (if that's what you would like).