I would recommend a set of Schwalbe Big Apples, the largest size you can fit (I use 2.15", my old steel hardtail MTB with fenders won't fit the 2.3"). Yes, they have a reflective strip on the sidewall, but it can be pulled off since it's only adhesive, leaving you with a black tire. I have 6500 miles on mine, regularly ride bad pavement, up and down curbs, down stairs, etc, and they're perfect. They're not an off-road tire obviously, but they do ok on unpaved surfaces.