The PSS is one of the best performing UHP summer tires in the wet! But when the temps drop below 40*, they will start to taper off on traction. With that being said... I recommend the new Michelin Pilot Sport A/S 3 PSAS3 if you are looking for the best all-around tire. Here is a quote from the BMW Blog review of it:
These Michelins are not intended as track tires, though you’d have me fooled through an autocross. To call them all-seasons almost seems disingenuous – they are just too good at everything: it seems to defy the category, which normally is mediocre at everything and good at nothing. In short, these are all-seasons that perform like summer performance tires yet can bring you safely home through light snow and slush.
Read the whole review here: