There are so many uncontrollable variables on this topic.
I said my HRTZIIIs are complete crap in wet. Well what does wet meant to me? Here in Sacramento it can POUR!. It's not uncommon to see bad storm where trees fall over,fences are knocked down and the liking. This to me is considered wet. I've hydro planned several times with the HRTZIIIs,each occurred when the weather was like this. Light to moderate rain,isn't really an issue so far.
Also my alignment is a little more aggressive then OEM spec,this can play into it as well.
Air pressure settings,play into it also...
The list goes on....we can argue this all day.
The links(tirerack) provided below are basically the most unbias,controlled test you'll see.