It's personal preference. Personally, I ride 155's, both with and without the turbo. I ride 9-13K', in Colorado, and the western US (Deep, Dry snow). Yes, a 163 would give me a little bit better flotation, but it would also hinder the jumping ability of the sled slightly. In addition, I ride a lot of tight trees, and even though it is only a couple inches of total sled length, I feel like I can notice it in the trees. That is my opinion, its free, but it also may not be worth anything anyone else. Form your own, by riding different track lengths and you will be happier than if you just listen to other people telling you what is "best"