What calipers are you using? I wasted 20 bucks on some crappy ones, and they never have a perfect zero on them, but they don't loose distance and are somewhat accurate. The Inland PLA I've been using measures anywhere from 1.752 to 1.61, which is a considerably smaller margin than your measurements. you can do a quick test by printing a stair step cube or something, but print it solid. If its over extruding, there will be blobs everywhere because unlike with infill, there is no space for the extra material to go.
Master Tinkerer