S197's have quite a lot of negative camber up front. Stand in front of it far enough back to see both tires. There is so much neg camber, you can see it very well. Unless you rotate the tires a couple of times a year, the fronts will wear out prematurely on the inside. It doesn't have all that much to do with the tires, except the wider they are the faster the wear will show up.
If your tires are wider than stock, you should probably cut 1500 to 2000 miles off your rotation cycle.
Camber plates are for people who road race and don't like to fly off the outside of a turn backwards at 100 mph. You can adjust them so you fly off the turn front first, that way you can see what you are going to hit.
Seriously, adjustable camber plates are good for the Mustang, in that they allow much more precise camber adjustments, but they won't cure premature tire wear completely.
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Bone Stock '07 GT 4.6, Redfire w/ parchment leather, Automatic.
If it looks right, it is right, and I decide if it looks right. Paraphrasing Sir Sydney Camm (of Hawker aircraft IIRC)