I wouldn't run a 17mm rim at all. I weigh 240; don't need none of that skinny stuff. But if I HAD a 17mm rim, and a 60mm tire, I'd mount 'em up and try it out. The largest tires I've ever used on my built-from-parts singlespeed, which has a fairly narrow (but unmeasured) front rim, is 41mm. No trouble at all with that combination. The worst that can happen is it rolls off the rim and you crash and die, but probably you won't. Why would Schwalbe lie?