Knowing the width of the rims would be helpful, but from my own experience, i'd guess you'd be OK down to 32 or so with any rim I've seen. Before I settled on 700x35s for nearly all my riding (I weigh 240; got no use for skinny tires), I swapped randomly from 23mm through 41mm on several sets of wheels with no problems.
Re 48mm tires: I've seen them a few times, and they're generally heavy, thick rubber. I think you'd notice a much different feel with a lighter, "roadier" 35 or 32, like a Panaracer Pasela.