Originally Posted by mechBgon

Road surfaces themselves have quite a bit of "tread." Unless you're on loose stuff, the minimal tread found on a road-type tire isn't too relevant, certainly not for clearing water from under the contact patch. The road surface has enough negative space for that.

In the bigger picture, as a commuter, what you should be most concerned about in wet conditions is wet manhole covers and slick crosswalk stripes, that sort of thing.