Any of the flat-resistant type tires would accomodate this need. Armadillos, Gatorskins, Marathon Plus are of suitable thickness and toughness. Have one 'rough' stretch on my 17.5 mi commute that's 0.5 miles of uncrushed gravel and my 700x28mm SMPs laugh and keep rolling. I ride a CX bike as a commuter. It has the clearance for 32mm or larger, but I thought 28s would be enough to replace the stock 30s that flatted within 2 weeks.