Per Outdoor Research, the large fits a size 9-11 boot. So you’d be right on the edge of what fits. If you were wearing a fairly slim boot (like a danner pronghorn) you’d probably be fine. If you were putting them on over big baffin winter boots or mountaineering double-plastics it likely would not fitI wear a size 11.5 or 12 usually. Would these fit or be too small? I read that you can get by with a smaller size for tighter fit?