I run 28mm tires on our steel tandem, 31mm inflated to 95 lbs. on 23mm outside rims, all up weight 325 lbs., love the ride. On my '99 carbon single, I run 23mm tires at 80/100 lbs, on the same rims as our tandem, all up weight 172 lbs., love the ride. If I were commuting in Seattle, I'd ride a different bike for that purpose with a somewhat more upright position, plus much wider tires at lower pressure. But I don't do that.
On my single, the load/mm is about 3/4 of that on the tandem, which already has a great ride. I don't see why I should reduce the load/mm any further at the expense of handling and aero performance. My butt was fine after doing 400s in my 60s, 15-18 hr. ETs. I wouldn't think that they'd have engineered the compliance out of new carbon bikes, but maybe so? Or not - I run the same tires on my rain bike, an alu $125 Bike Nashbar frame. I guess I don't understand the issue. If it ain't broken . . .
Maybe position makes a difference? I run a good bit of drop and lots of reach. My hands don't really notice any vibration, alu stem and bars. Oh yeah, all my bikes ride horribly on rumble strips, are only OK on the local chipseal, but there's not that much of it. For sure Texas and Montana chipseal is another animal.
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