I just did my first ride on 25c tires yesterday. Both the old 23c and the new 25c are Continental 4000S.

I weigh about 170 lbs.

The 23c tires were at 95 psi front, and 105-110 psi rear. That's my normal inflation.
The 25c tires were at 90 psi front, and 102 psi rear. That seemed fine. I unscrewed the valve and "burped" maybe 5 psi out of the front during the ride, and it was still good.

I'll have to experiment some more. Looking down, I saw no sidewall deflection on the front, and the normal amount on the rear. I'll probably try 85 psi front, and 100-105 psi rear--to avoid pinch flats.

The old 23c GP4000s were very good on rougher roads. The new tires seemed to soak up the rough roads even better, but it's not a blind test, of course. I like them a lot, so far.

Continental says the weights are: 23c 205 grams, 25c 230 grams.

You have to look closely to see the tire size difference: