Will 255/45/17 summer tires clear the 968 rear wheel wells?

Stock rear tires for my 968 are 255/40/17's, but such low aspect ratio tires ride HARD over the bumps.   Just the jump to 45 aspect ratio tires (like the fronts) would make a difference , I feel.    Years ago the 255/45/17 size weren't available for many tires, so is this the reason for the low aspect tire requirement in the rear only?    Or is there a clearance problem?  Continental Extreme Contact performance summers are available in that size now.   Any input appreciated.   Anybody ever try this?