"My opinion is that gravel- and dirt-road riding is no harder on wheels and frames than paved-road riding, and in many cases is less stressful on them. I have no test data to back this up, but I have years of dirt-road and cyclocross riding as evidence." - Lennard Zinn
Makes sense to me. I would think that running larger tires at lower pressures, to absorb more vibrations/shocks, would cause less fatigue, over time, than running smaller tires at higher pressure, and transmitting more.
