I have those exact Bridgestone tires and my X is doing the same thing. I do agree that the negative camber is causing this unusual wear pattern, but is there much of an adjustment that can be made (to a point of -1 or 0 camber) since the X was designed to have a bit of a negative camber (-4 in the rear, I believed) to begin with? At some point, I might consider dismounting the tires and put them on opposite wheels (move the wear side to the outside of the wheels) to try to get more milage out of it. But I'm not sure if it's cost effective due to all the labors involved to get a few extra miles (mounting/dismounting, rebalancing, and the most important one...chances that those tire tech will damage my wheels in the process).

Staffop, increasing the tire pressure may help, but very minor. I'm already running my rears at 35-36psi since new and I'm seeing same problem as you do. So, the only other thing is try an alignment as others have suggested and see if the shop can get as much of the negative camber out as possible.