It depends on what you need a tyre to do, generally an all purpose tyre
is called an AT (all terrain) but the tread design of those might even
be too aggressive for what you need.
Best go to several tyre shops, tell them what you want the tyre to do
and see what they recommend.

Daryl

most of the "AT" types are ok, almost road tread(except for the BFGs)

Kev

All Terrains or A/T's

Thanks for all the replies.  
There would be some secondary, unsealed roads  e.g. to
Birdsville Qld from the east,  plus some of the unsealed bits a short way off
the main roads to scenic spots, the kind of places you would hesitate
taking your sedan. Having worked 4WD's on steep hillside
farms I'm well aware of the limitations of an offroader. If the BFG's and
Coopers A/T's are a bit growly on the tar, there is a selection of Kumho
A/T's at reasonable prices - one of them I looked at was the Road
Venture AT D825 (unfortunately the Kumho Australia web site is under
redesign at the moment).  My AWD/4WD  is currently fitted with  Bridgestone  
Dueler H/T 687's which are strictly onroad rubber. I'll keep looking around
the brands - it's always good to get an honest opinion from a user rather
than a salesperson.

cheers

Brian I've had good wear and performance from Kelly tyres. They spend most
of their time on the tar, but have done the GCR,  GJT and Kidson Track
without drama. They aren't a particularly aggressive tyre, but wear well and
I'd buy again. Unfortunately I've been told that they are no longer
availiable. Just how true this is I'll find out when my second set wear out.
But it will be a while yet , as my second set have around 60K on them and
don't look much different from new :))