I run 245/45/18 Hankook Ice bear snow tires all winter long. And i have been herd of guys running 235/50 Front and rear.
Currently i have 255/45/18 RE760's on the front and 235/50/18 Goodyear GS-A on the back with no problems.
And i bought a set of 235/50/18 Blizzaks I plan to run in the future.