I know about the 8 inch spring with coilovers. According to MM you can't do that with a full weight car because of coil bind especially on the street.18x10s are relatively easy. The rears just bolt on. The fronts you need an 8" spring if your running coilovers, a little fender rolling, and a decent amount of camber(probably -2 or more). This is an old pic of when I had 18x10" +22 with 285/30r18s. The car was basically just a MM max grip setup at that point.
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I'm trying to do this with a 10 inch spring, a small spacer and pulled fenders.
Additionally my car is an 03.