OK, I just went and double-checked myself. Currently mounted are the Little Big Bens, 700x38:
http://www.schwalbetires.com/bike_ti...little_big_ben
On the shelf are the Marathon XRs, 700x40, no longer made but they have a good rep.
Apparently I conflated the sizes. I didn't remember what I had on the shelf, which are the ones I was going to mount. The bike and fenders will certainly take 48s if I need them.
I know, I should be cross-posting this on the Clydes group...
- Ed