road ride 1:00:10  15.5 mi (3:53 / mi)
running new 25mm puncture resistant tires on the rear up from 23mm. Still using 23's in the front. Ride was much smoother. This was due to a combination of the wider tire and using lower air pressure (100PSI vs my normal 120).
I should have used 120psi. I would have been able to better gauge the difference. Bike felt a bit sluggish but then again - was it it me, was it the tire pressure, was it the extra 2mm's??
In the end my time was good. Contrary to what people would think, the consensus is that 25's will result in a faster ride. In part because the smoother ride lets you be more aggressive. Also static friction is reduced. This is not what I would have thought.
There must be some truth. 17mm tires are a thing of the past.