Originally Posted by
coldbike
Fast tires generally have supple casings so that they lose less energy when they deform from road imperfections. The most flat resistant tires will be less supple due to the flat resistant layers.There are tires (like the Marathon Supreme) that try to compromise, but in general flat resistance comes at the price of speed.
I see - in your experience how much of a difference might we expect from this factor? Imagine two sets of tyres with the same width, shape and weight but one being however much stiffer than the other, due to puncture-protection.