Iv heard really good things about the new KO2s, but the smallest rim size is 16in
I personally was torn between the kevlars and km2s, but then everyone in my area couldn't get the kevlars for 3 months so I went wight the km2s. I DD them and they arnt noisy and stop well. If you dont want something quite as knobby, id say go with the KOs. My buddy has them on his raptor and we have hit 100+ with no issues from them, and the sidewalls feel stiff on mountain roads. We have also done some wheeling on them and they hook up well!
As for size, go 12.5. The few times you do off road you will like the extra bite.