I used to recomend the KR-21's often to friend/family but, after seeing them in a short period of time/mileage, they wore fast often viberating.
The KR-21's started out great and those who had them new, loved'em but, they just didn't hold up.
If I could get them cheap(as usual) and I had a car that needed tire to sell the car, these may be the best of the CHEAP tires. Or those tires that you only need for a short period of time until you sell your vehicle.
The KR-21's performed quite well when new. They:
Balanced well
Good hydroplaning resistance
Good snow/ice traction
and many other things too...see their reviews/scores