Why are you running such narrow tires on such a big wheel?
I get it that you maybe want some more speed out of your hybrid, but really get some 32 or 35 and inflate those to about 50-60 PSI and call it good. I ride on 42 at 45 PSI and my bike is plenty fast (for urban use).
If it's speed you're after, perhaps you should get a cross or road bike.
Acording to Sheldon Brown site, you want 13 to 17mm rims, internal width, for 25mm tire.
http://sheldonbrown.com/tire-sizing.html#width