Challenge Dune (small shoulder knobs, running along a diamond file tread) or Chicane (bigger shoulder knobs running along a diamond file tread). The Chicanes were my go to tire for several years riding loose to chunky (not boulders, but bigger rocks) gravel. I'm login to run the treads off the Spesh Pathfinders my bike came with, then mount the Challenge Gravel Grinder (essentially a Chicane, in bigger volume). The tread is durable and hooks up well. I've never ridden on the big island, but I recall the "gravel" was sometimes treacherous with the volcanic rock, I'm sure you're taking this into account since it may chew up the tires pretty good, depending not he surfaces on the road you will ride.