the type of tire will determine your traction. the diameter of the wheel has little, if any, effect on the traction.
coincidentally, the this month's auto club newspaper mentioned that on light snow, summer tires took 65 meters to stop from 50 KPH while winter tires only needed 30.
four-wheel-drive has no effect on braking distance.
i have michelin alpines for the winter and my X5 can climb anything with them on and can stop when it needs to.
get winter tires.