BTW, I have been commuting on Conti GP 4000s in 25 mm with no problems with flats and excellent wear. My Conti 25s do running narrow, about 24 mm wide, but my rims are Open Pros, which are only 19.5 mm wide. I suspect that on a wider rim, they would measure close to their nominal size. Anyway, the Conti 28s should be noticeably wider than what I have been riding on. I ride this bike commuting 99% of the time. If I do some loaded touring, I will probably put some larger tires on for the trip.

I am well aware of how much tires vary from their advertised sizes. Michelins used to run large, but apparently the newer models run small. I've got some Michelin Pro2Races in 700 x 25 that actually measure 27-28 mm wide on my Open Pro rims. Very nice tires and it's a shame Michelin quit making them the same way.