I do not mean to sound like a jerk, but, I have to ask, so with a 170 you have slower turn in, as I mentioned, and the tire is actually a bit heavier and a bit more expensive...and whether you beleive it or not, a 170 on a rim made for a 160 is actually pinched so the profile is distorted and your contact patch may actually be SMALLER than a 160.
So what is the real benefit? Lower RPM? Wouldn't a larger front sprocket at a cost of $15 be a better option than running a tire that is heavier, more expensive, distorted and offers slower handling?
Sorry, don't mean to sound like a jerk, but I am trying to give the OP some sound advice, and to me, I just do not see why you would want to run a 170 on this bike, I see zero upside?