dwight

My Kumho ASXs weren't that good in light snow. They still have about 6/32" tread in the front and 4/32" in the rear.

ZDan

FORGET the stickie.
Thing 1: Greater tread width does NOT mean a bigger contact patch.
Thing 2: Even if it did, more contact patch does not necessarily imply greater traction. Tire make/model, compound and construction are infinitely more important than outright size.

All things equal, a wider tire will generally give greater ultimate lateral grip when fully warmed up. BUT, more propensity to hydroplane in wet conditions. And since you're talking all-seasons, you're going to likely be better off with narrower tires in snow/ice conditions anyway.

The grip advantage of wider tires isn't even that much in ideal, at the track where you can get full heat into the tires, in warm dry conditions. My fastest time at Watkins Glen in my stock '01 was 2:20.5 with 225/50-16 front, 245/45-16 rear Kumho VictoRacer DOT R-comp tires (brand new that event).
The next year, under the same conditions, no driver improvement (been to WGI many times), I did a 2:21.4 on narrower 205/55-16 front, 225/50-16 rear Dunlop StarSpec *street* tires.

There just isn't anything much in terms of real-world grip with wider tires. Particularly for all-seasons, there's not a compelling reason to insist on 245s.

Go with one of Jim's suggestions. Also, go to the Tire Rack website, TONS of info there.