I'm about done with my 622x38's, stock conti's that came on my Surly Disk Trucker. I've done close to 70 miles the past two days on a trail we have around here and it is rough - real rough. I've been throwing around the idea of softer springs for my Brooks Flyer seat, but haven't come across the right springs yet. Thing is, no matter what the springs are in the seat it isn't going to help the frame and racks from a day long beating every time I go out.
My neighbor has a mountain bike with some pretty fat tires on it, aired down further than I'd think. We got to talking today and the reason hes running that is because of the terrain around here. He rides almost all roads and trails, but they're in crappy condition.
Just thinking here.. maybe if I put some thicker tires on with less pressure I'll be better off. I have my tires at 65psi right now and with my rack loaded up today I could see the rear tire bulging just under the weight, let alone hitting a bump.
It doesn't look like there are a whole lot of tire offerings in the 700c class that are much wider/thicker than 38-40. I'm also not looking for an off-road style tire, something with more street tread is what I'm after vs. mountain bike knobys.