I have an 02 ws6 with zr1 wheels.8.5 in the front with 275/40/17 sumitomos.The rears are 11 inches wide with 315/35/17 sumitomos.I have tsp true duals too.My question is which springs will be best for clearance and wheel rub in the fender well.I want it low for the aggressive look but don't want to regret it either.Anyone with experience please help me.Pictures are helpful too.My car looks like a 4×4 right now..lol.

 

I'd say shoot for a 1-1.25" drop. Any lower and you'll probably start hitting the pipes on speed bumps.

Look around at different springs, determine the spring rate you want and find something you like.

 

I installed Hotckis sport springs that lowered ther rear 2 inches and I ran into the same problem, wheels rubbed so I installed shackles on the rear of the springs for a 1 inch lift giving no wheee rub on launches. so I ended up with 1 inch drop and can always lower the shackles if I ever go with smaller tires.