240s have a wide lip on the wheel arches that is particularly thick (three layers of sheet metal, IIRC).
So not only does it intrude into the wheel wells more than most, it is far less willing to 'conform' to the tyres' needs than most.
Cut it and fold the remaining lip back. If you don't cut it, then there's a lot of thick sheet metal to fold back.
One of my old GTs had 17x9s on the rear, with cut & folded lips. I managed to make the scrubbing minimal by dropping the tyre size by 10mm (sorry, can't recall if I dropped from 235s or to 235s), and carefully machining the wheel spacers to get each tyre centered in the wheel well. There MIGHT be a thread on the car in Member Rides from several years ago.
The small amount of scrubbing still annoyed me.
