As far as I am aware the max demonstrated X wind for a PA28 is 17mph........which is 15Kt.
As said this is simply the maximum crosswind that a test pilot operated the aircraft to during flight testing.........everyone is entitled to become their own test pilot and try a higher figure but I bet the insurance will have a get out when it comes to test flying so perhaps one should pay the loading that the insurance company will put on the policy prior to it's intentional use for test flying.
Getting caught out is something different!!
Remember that when it comes to gusts, they are only reported when the reach 10Kt above the mean.
Thus 180/15 could be 180/15 or it could be 180/15 gust 24.....one has to look at the bigger picture or call for an instant wind report.
Also the variations in wind direction have to be quite large before they are reported in the routine reports so being on the limits cand be fraught with danger for the unwary.
regards,
DFC