I have a 1996 Z28 with rims 18 X 8.5 front/ 18 X 9.5 rears and tires 245 40 front and 275 40 rear. The problem is that when I go over a dip or bump in the road the right rear tire scraps the wheel-well. The shocks have been replaced with KYB shocks all the way around (on setting 8 on the rear). I want to replace the springs, but all the springs I see drop the car. There is plenty of room to lower the car but I don't want to end up with same problem. What I'm basically asking if I replace the springs with lower stiffer springs will it fix the scraping or not. Thanks.
Jeff

 

Your wheels have the wrong backspacing.

You can change your wheels or roll your fender lip.

 

Thanks guess I will have to try and roll the fender.

 

An adjustable panhard may help, it will let you pull the axle toward the left.

 

I think your overall tire diameter is also too large. Typically 40 series tires are used with 17" diameter wheels. You may need to look at 35 series tires.

 

Bud M: If I use a adjustable panhard, could I install it myself or should I have a shop install.

OBE1 95Z28: Thanks when I order new tires I will try that too.

 

You can swap out the panhard easily in your driveway. Assuming you have the right tools. May take a breaker bar and some PB Blaster.

By my calculations your 275/40/18s should only be about 11/16 inch taller than my 285/40/17s. That's about 3/8 further into the wheelwell. With stock springs you should have adequate clearance. My car is lowered over an inch so actually I have more tire into the wheelwell than you with no scraping. So check to see if your rear wheels are off center in relation to the fenders. Also wouldn't hurt to check the condition of your panhard bushings and swaybar bushings.