I need a tire that can do everything.

Ho-kay, after being a smooth-road-only rider up until recently, I've discovered the fun that is a cyclocross bike. There's this loop right out my door that I've been enjoying lately, it includes a couple of miles of road, then a series of fairly dense gravel roads, some more asphalt, and then a bunch of singletrack (I think that's the term), with a few STEEP short sections and barriers to cross. Most of the singletrack is hard earth, often quite choppy.

I've discovered that my Schwalbe Racing Ralph cyclocross tires aren't quite what I need to generally ride around on this surface: the soft rubber compound isn't durable at all, and the frequent blackberry thorns just tear through them.

There's enough dirt and gravel that I'm betting a "road tire," even a fat one, wouldn't be what I need, though I'd love to be able to run high enough pressures that cruising along the road isn't entirely sucky.

Recommendations?

Smooth rolling for the hardpack and road but can handle some offroad?

Try a Kenda Kwick or Ritchey Speedmax. Both are affordable and have similar semislick tread patterns.

Kenda Kwick
<img src="http://www.nashbar.com/nashbar_photos/medium/K8-KWKCC.gif">

Ritchey Speedmax
<img src="http://www.webcyclery.com/image.php?productid=16420">

As for thorns, there aren't many completely puncture resistant CX tires out there... I would look into some Mr. Tuffy's or Slime...

From experience I can recommend the Conti Country Ride; WTB's All Terrainasaurus; the Michelin Transworld Sprint; and maybe Panaracer's T Serv. They are hybrid 700c tires in various widths that are strong and puncture resistant, reasonably light, and have decent tread for varied terrain. I've used them on my 'cross & singlespeed bikes in the conditions you've described, with good results.

I have to disagree with the second poster. My lady has the Kenda's and I have the Ritchey Speedmax's on my cross bike. Neither is a very good tire on the road - they both have significant resistance and noise. Don't get me wrong, they're great tires for 'cross, but are no good for pavement.

What I really like for a do-it-all tire is a pretty cheap solution - the Ritchey TrailMix. Here's a link at excel sports (haven't seen them at too many other places): http://www.excelsports.com/new.asp?page=8&description=TrailMix+Tire&vendorCode=RITCHEY&major=8&minor=2

The main thing you want for a road worthy tire is a semi solid center section of rubber (See the TrailMax vs. the Speedmax or Kenda). Another bonus is that the TrailMax is made from a much more durable rubber compound. I have used that tire for both single track and commuting. It is much tougher than my foldable Ritchey SpeedMax tires. Off road traction is pretty good at lower pressures, I run it at 60-70psi for commuting (I weigh 180lbs).

Downsides? The tire is not super light (but who cares for a multipurpose tire) - but about the same as the Kenda. It also only comes in wire bead - which is a bonus on the price - I think the retail is $15.

Tom