Castering and cambering, of course.
Sharad's Helpful Hint regarding S197 Strut Mounts:
For many years, the 'Net Nerds have insisted that if you lower a Mustang, you need to install Caster
Camber Plates to properly align the car. But what does it mean
specifically to "properly align" a car? Is it a street car, drag car, or roadrace car? What is the current
suspension setup? Is it slammed? What size tires are you running? Can you rotate them? And so on...
I can tell you from personal experience with my S197, that my camber was around -1.2° from the factory which is good for nothing but tire longevity on a cautiously driven car. When I lowered my car about an inch while still using the factory strut mounts, it changed the camber to -1.6°. With my fairly aggressive driving style, including one HPDE at Sebring International Raceway, I went through a set of Nitto NT05s in around 25k miles, with one front to rear rotation, and the tires were evenly worn from side to side. Later, I lowered the car 1.5" total and installed FRPP GT500 strut mounts. With the non-adjustable GT500 mounts, this dropped my camber to -1.8°. I've almost worn through a set of Goodyear F1 SuperCar tires in staggered sizing (no rotation) in about 15k miles (including one auto-cross event), and the fronts are still worn almost perfectly evenly. That is to say, there is no significant tire wear due to the additional negative camber.
On the contrary, the additional negative camber (from -1.2° to -1.8°) has improved the turn-in, making the steering feel more precise. You'll find that most of the racers who run adjustable caster
camber plates on S197s actually run 2-3 degrees of negative camber. So in that sense, the negative camber introduced when you lower an S197 with non-adjustable plates actually IMPROVES handling and does not accelerate tire wear. Regarding Caster, our cars have a good amount of caster already, around 8°, so you don't really hear of anyone using cc-plates to add caster.
So there's my two cents. Even though my employer sells camber bolts, and I have connections to score a discount on adjustable cc-plates, I don't run them on my car because the caster & camber on my car are pretty ideal, even with non-adjustable strut mounts. I simply had the toe zeroed out and adjusted the
panhard bar to center the axle when I lowered the car.
Hope this helps. I would've made recommendations specific to MyJayy's original post, but when I asked him to elaborate, that seems to have put a target on my back.