Just had two new tyres on my 2.0d superb estate. Firestone zs90. It had dunlops on previously with no issues. The ride is definately not as smooth and the slightest road imperfections seems to be transmitted to the wheel....

Had the wheels balanced (twice), and the car has just had it's first service where I asked them to check everything - no issues...

Any experience of these tyres here? Are they just poor? Next step is to move them to the back....see if that helps...

I've no actual experience of Firestones, but you could try dropping the pressure 2 or 3 PSI. If you do that, keep an eye out for under-inflation edge were though.