I think what the tyre fitting palces say is just BS! In my experience, new tyres are always best on the "driven" wheels, reason purely because then they will bed in and lose their crappy sheen so much quicker.
I had an Xr2 about 15 years ago and tyre place put new tyres on the rear.............about three weeks later, and near 800 miles on them, in the wet, I had to brake very hard as a car pulled out in front..........the back just started fishtailing, it was a mare. When I looked at the tyres later, the bobbles were still on them, even some of the glue from the sticker was still there! No wonder they lasted 40 k miles on the rear! !
So never again, always new on front now, and if I have 4, I do a couple of hundred on the front them swap front to back.
S3 I count as FWD.!!