I wonder if this chassis would benefit from wider front tires than rear, so I’m seeking feedback from chassis guys. The RS3’s sport package option has a similar setup. I realize that cars in that Golf/TT family drive very differently (like a FWD). I think the S4 has a natural tendency to understeer, which is counteracted by the sports diff. The question is whether having better grip at the front end would benefit the car more than the differential in traction on the outside rear tire. A possible downside could be the car would not want to turn in as easily with a front that wide. Another unknown is whether this type of quattro system would break with a front tires 0.5" taller (I think the answer is no). I think the benefits are that the front tires are being asked to do A LOT of work - carry 60% of the static weight, heavy braking, and a lot of turning. My fronts wear faster than my rears. I don’t rotate wheels.
Anyway, for practical purposes I’d keep the 255/35ZR19 PSC2 with a 19x8.5 on the rear, and substitute a 275/35ZR19 PSC2 with a 19x9.5 in the front. I think I have front fender clearance with the high camber. I have no more clearance on the rear - the PSC2 runs quite wide and I suspect it could touch the fender (rear bumper cover edge) when the car is in motion. I can see it starting to peel back.
I’m not committed to this course of action, just seeking feedback.