I don't find the ridge grapples very good in icy conditions. No siping and too big a lug. I run them most of the year,but not winter. I have tried them in winter though. As far as all terrains go I find the BFG Ats to be the best. I've run toyo Ats in the past and not as good, but got way more mileage out of them. Going to a harder compound sacrifices winter traction. Going to a 275/60 or 65 series 20" will help a little as narrower is better in snow to a point. Virtually any winter specific tire will hugely outperform any all terrain in the ice and snow. I run hankook ipikes. I stud them, but they're good non studded as well just lose some ice performance that only studs can really provide. Even in their 4th season for me, which means about 60,000 miles+ they still outperform any all terrains I've had, but I usually only go 3 because I deal with super icy roads all winter for long distances. Given that you're looking at occasional winter driving an all terrain will do the job fine, but if you're going to be putting on major miles and going through tires then you might as well get snow tires and a spare set of wheels. Just end up buying more tires less often and if you buy used wheels you should be able to resell them for minimal loss if you sell the truck.
