Change of tire size?

You should be fine. The 16's are a little shorter and narrower, but within spec. I have to mention it though, but you will also need 16 inch wheels with the same lug pattern as well.

You would have to swap to 16 inch rims first. Just verify new smaller rims aren't going to rub against calipers.

As far as tire height and width you should be fine, but go to a wheel/tire comparator site and put in the wheels you have now, specifying their offset and then the ones you are intending to use. The same site will almost always give you an estimate of how much your speedometer reading will change from one size tire to another.