I ride at pretty much the same speed as you but almost always by myself in some out of the way rural areas. Minimizing flats is my hot button, couldn't care less about a fraction of a MPH, even assuming the difference would be measurable in my case. I have only Conti Gatorhardshells on my bikes. I had some trouble with rimtape from a few months back, but other than that I've worn out 2 sets (over 8000 miles) with one flat. And that piece of road debris would have flattened a truck tire.