All dirt roads are not created equal. Is it wet, sandy, rocky, hard packed etc? The wetter the better until it turns to quicksand. I usually do not run more than a 25 on gravel in either Conti 4000s or Gatorskins. If it is more rocky, the sidewalls on the gatorskins are a plus.
However, a wider tires helps on descents. If you have some sharp climbs/descents than look at the gator skin in a 28 or a rivendell rolly poly in a 28. It is a good tire.