Originally Posted by
meanwhile
What have you tried? The adventure touring people seem very happy with either Marathon Supremes (ultra fast touring slick with some off road capability, especially in the wider sizes - I'd go 40mm) or Extremes (said to be about the fastest treaded tyre you can buy; excellent road handling - ie doesn't suffer tread flexing and "walking" in tight corners.) I've read posts by people who even use the Extremes for MTBing, up until the point they need a tyre with high speed good cornering in mud.
In defence of my current Weird Turquoise Michelins they're great off road and fast and even corner well on tarmac. Just a shame they can't brake there too...
Only tire I've tried for off road and on road is the Specialized Borough CX. I'd say that this works ok off road as long as no climbing is involved, but they are quite slow on the road.
I've heard great things about the Marathon's. Might be worth a shot. If there exists a tire that could do good on both surfaces (nothing extreme offroad) then just going for a ride as the OP originally asks would be very easily possible.