according to Soma you can get up to 47mm tires on there. You won't regret putting the fattest tires on there for any kind of bumpy dirt roads. If they aren't bumpy dirt then 35mm is a great size for your weight on paved roads but I'd try and get 40mm+ tires in there for bumpy dirt. Put a tough sidewall rear tire on if you're carrying weight there. Sidewalls suffer sliding off/through half buried rocks.

700x37/42 Continental Travel Contact
700x37 Continental City Ride
700x38 Schwalbe Marathon Cross
700x38 WTB All Terrain (front)
700x40 Schwalbe Marathon Mondial / Supreme /Dureme
700x38 Specialized Crossroads
700x42 Specialized Hemisphere