I ran 245 35 18 A6's up front. I remember you ran the AD08's, so I've attached some pics comparing the 245 A6 to the 225 AD08. Converting to mm's (inch * ~25.4), both tires are very close to their advertised width.

Early in 2012, I did get a deal on 235 35 19 A6s, and when I mounted them in the back, they were actually just as wide as the 255 tires. As you know, the rim width will pull in wider tires, but they also gave back a little on the narrower tires.

I'm running a 1/4" spacer up front, and have the camber bolts, and I'm running around -1.8 +/- .1. I have worn the outside corner first on all sets of tires, but the treadlife I'm getting -- about 100 runs of 50 second Autocross-- is about typical. I'm not sure you would more than 10 - 20 more runs with additional camber. And I can't complain about the grip performance.

When the Z214's, first came out, about 4 of us all tried them at the same time. Main reason -- price. No complaints about the grip, but all of us noticed some cupping on at least one of the tires per car on the outside. Not sure if it was a production defect, or what. None of us noticed either a performance reduction, or faster treadwear, but it was a little distracting to see the unusual wear.

I would be happy if either the Z214s came out with a 19" tire, or if I got some 18" wheels, wider than the stock XF front rims.

All of that added up to a first place finish this past season in "D" in our local NASA club. The NA is an "E" car, but with SRT brakes, shocks & springs, Needswings CAI and Eurocharged tune I had to move up a class, but it wasn't a problem. I also beat a lot of C, B and even some A cars. Good Luck, and keep us info'd. We are all living vicariously through you.
Mike