No spacers, no rubbing whatsoever. You really should have either the OEM Sport Classic or OEM BBS wheels with the 11.5" rim and 63 offset though for the 315 width tire.Front wheels: 9.5X20 et65 275/40/20 Continental DWS06

Rear wheels: 11.5X20 et63 315/35/20 Continental DWS06

 

Thanks for the reply.
Sorry for not mentioning my ride. Mine are 13' s with Turbo II Wheels OEM 9.5j x20 ET65 and 11jx20 ET68 currently with 255/295 pss, just wonder if I can go for the 275/315 combo without spacers which local installers won't do the spacers.

 

The tires may still fit in the rear, but I can not say for sure. It is safer to use the OEM Sport Classic or OEM BBS rims that have extra half an inch in rim width and 63 offset, no issues whatsoever with either of those two rims. You can usually find a decent set used on Ebay for $1500 or less. Better safe than sorry.

 

The whole ideal of big tires with big wheels is counterproductive in that it does not make you go faster. It is just " cool." That's all. "Cool" has it merits, but there are limitations. First consider "rubber band" 22" sidewalls. Have you ever seen a competitive 1/4 racer with 22s? The reason is that the actual contact patch is smaller with rubber band tires. That's why you see "wrinkle wall" tires on racers. I suppose wider low profile tires might make you a bit faster on the track. I don't know what Porsche mounts on its Panamera record runs at Nurburing, but I think it is safe to assume the combination Porsche uses there might just be optimum for amateur track usage.

Then consider reciprocating weight which includes crankshaft, pistons, rods, flywheels, drive shafts, gear assemblies and tire/wheels. Reciprocating weight reduction used to be dismissed as an unmeasurable myth. With recent dynos, like the Superflow SF-800, one can measure hp/torque differences in reciprocating weight.
Lets be specific: I owned a very nice '14 Panamera S. It was used and had 19" OEM wheels with all-season Continental tires. I weighted the tire/wheels. The fronts weighed 66lb and rears weighed 67lb. I wanted a set of wheels/tires for winter and chose 18" OEM wheels (fronts only) with Michelin Ice winter tires (same size all around). Weight was reduced to 52lb each. I'm an 80 year old geezer and my race days are long ago. I drive mostly like an 80 year old man, but sometimes I do punch it a bit. Most of my performance measures are simple, like how fast can I drive comfortably around a familiar coverleaf? . With the 18s I did notice minor lessening of cornering on my cloverleaf, but this was at the limit of tire adhesion, where winter tires are always lesser. Gas mileage definitely improved.
I sold the '14 and bought a '17 Turbo with 20" wheels. Turbo front brakes are huge, so cannot put smaller wheels on the fronts. I still have the winter tire 18 set, and may mount two on the rear.

 

Tractiom, handling will both increase with the 275 40 20 front, 315 35 20 rear setup, plus your speedometer will be more accurate.