I know exactly what your dealing with. I had KU31 Kumho's all round on mine and the road holding was good as was the handling but after having the car serviced and MOTed I needed new rears, not wanting to spend a fortune on tyres because I want to get some new wheels. Well since having Nexen N6000 fitted the grip is reduce by a considerable amount, traction light kicking in on corners where the Worn Kumho's would not let go, switchy in a straight line, turn in increased but due to the rear sliding earlier than before and a general lack of confidence in entering corners, the only bonus is that now I am looking much harder at new wheels as I want my Roxy but to how she was.