agreed
i've got 265's on the rear, and i've been told they reduce economy, i find it hard to believe, but it's possible.
i have to say driving style makes a huge difference. when i first got the car, was getting 250 to a tank, now i've eased up a bit, getting around 320.
my most recent result is 13.3L/100kms. (1200kms on 160Litres)