Are you selecting to Convert CMYK using the LAB values?
In CS6 the Pantone solid libraries are always defined as Lab—as far as I can tell the Ink Manager's Use Standard Lab Values no longer has any effect.
So these libraries are now defined as Spot colors with Lab definitons–if you convert the spots to process via Ink Manager your document's CMYK profile makes a color managed conversion:
If for some reason you want a predefined CMYK mix (but for what press or device?) there is Color Bridge Coated and Uncoated—those colors are defined as process CMYK. So you could delete PANTONE 173 C and replace it with Color Bridge Coated PANTONE 173 CP.