[enjoythemusic]

Have the PS4S on the 435i (704 suspension, 19" staggered M rims) and love them. Yes the sidewall is softer than a RFT, which is normal for any RFT versus non-RFT. On street the PS4S are indeed grippy sun or rain, and turn in is very good and progressive at the limits. They provide very good feedback. You may want to raise your pressure by 2 to 4 lbs over what it says on the door label to 'stiffen' the sidewall a bit, then play around with pressure range until she feels / works as you prefer.

And of curse overall mechanical grip potential is far better with the PS4S than the RFT, yet am sure you already knew that.