i'm kinda surprised you fit a 11 lashed in a medium cartel. Lashed are the bulkiest boots i've ever ridden, and they broke down super quick. I was quite dissapointed with them. As long as you can fit your boots in them somewhat easily and do not have the straps maxed out I would try it.... but the fit will be that much worse once you get a little bit of ice and snow built up in your footbeds. You should be ok on the 158 with size 11's. Just make sure to center your boots so you have the same amount of toe and heel overhang.