Nice thread with great tire info!
I run the K270, in the 5.10 size. I really like it... no complaints. Does well in snow, sand, dirt, and mud, as well as pavement and gravel. But seeing the weight comparison, I can see why people would go with the lighter version. Honestly though, I can't imagine a tire being 5 lbs heavier than another of the same brand and tread design, just an inch wider and taller...
Specs: (copied from above)
4.50-18, 26.90", 15.28lbs
4.60-18, 25.65", 11.60lbs
5.10-18, 26.90", 15.08lbs
120/80-18, 25.88", 10.39lbs
Looking at these, it seems a little off. Who knows...? The lightweight versions must be thinner rubber and have small nobbies... I'd like to get the weight of a stock TW front tire. Mine felt light and weak. I could collapse the tire (vertically) with ease... whereas the K270 was firm and not collapsable. I liked that and see it as an upgrade.