Just as a personal point of information - I find 35s to ride harsh on the rear of my Crosstrail, while having no negative effect on comfort on the front. I also find 40 on the rear much more comfortable, no harshness, and no loss of "speed" or handling back there. On the other hand, the 35s are much more precise, and quicker handling on the front, with no loss of comfort.

I wouldn't be afraid to try 32s on the front, but I ain't giving up my 40s on the rear..................

I run my tires at 92 PSI, because that's where they roll the best (Yes, I know they are rated to 85PSI.) My Schwalbe Marathon Supremes run almost exactly their stated width, on an 18mm wide (internal) rim.