Why would raising the ride hight effect the turn in? That's what your doing with the rear when you go from 190/50 to a 180/55 and that speeds up the turn in?

Is it because you've lengthened the wheel base very slightly and altered the rake? So in that case turn in would be quicker with a 60, but there is less tread area so when cranked over we are running right on the edge of the tyre area, but would this matter on the road, when its rare that you get a bike that far over?

I had a 748sp with pirellis as standard which were dead good. After some years of sticking with them I found they wer'nt so good. This could have been down to suspension settling down or maybe the compound getting harder over the years. Pirelli and Metzeller are the same tyre, made by the same tyre company, just with different tread designs. I did find after some lower gearing that my 748 used to wheelspin in the wet. I eventually changed to Dunlops, its a matter of choice really.