well I got a set of c6 5 spoke 19 in the rear 18 in the front. The guys on here told me to get 1.5" spacer in the back of my trans am to fit the rims, but then my fender would scrap the top of the tire with bumps or passengers. I got some kyb shocks and oem replacement springs and some bushing(sway bar) the still scrap not as bad but still really scary with the eagle f1's back there($$). what the hell do I do to fix this? Is the only solution to roll out the fender walls? Also I found the kyb not even as stiff as the stock ones??? even though they r advertised as 15% stiffer.

 

Do you really need that big a spacer?

 

well 1.25" is the least 1.5 just looks better and the extra 1/2" didnt effect it because its hitting ontop of the tire not the edge

 

The solution is to run a wheel/tire combination that fits properly. You are trying to change the suspension to fit stuff that is nowhere near the stock fitment. Shocks and springs can't change a body to tire interference issue that results from improper fit.

Thinking it can is like saying different shoe laces will make your size 11's fit in a size 10 shoe.

 

I have 19x10 C6 wheels on all four corners... no scraping (yet). '98 Formula, 6 speed, UMI non-adjustable rear suspension/tq arm/SFCs.
I am running a 305/30 Michelin PS2 and 1.5" spacer on the rear (only gained 6lbs, each, including spacer and extra lugnuts, over the stock 16s).
I cut a full coil off my stock rear springs ('98 w/110k miles), which lowered the rear about 1"-1.25".
I have a UMI non-adjustable panhard bar and the rearend seems to be centered pretty well under the car.
I have the stock rear sway bar (smaller 19mm, I think), but will be upgrading nto match my Strano front.
I did some BFH'ing on my inner wheelwell, just to be 'safe' (mostly because of the tire's width), but the 1.5" spacer/adapter really helps on clearance to the inside. I have NOT rolled the fender lips. I cranked the right front of the car HARD/HIGH with a floor jack and got the left rear tire to tuck up into the wheelwell without scraping (more concerned with this side, since I weigh 220+). Of course, this doesn't simulate a sharp jolt that impacts both rear tires simultaneously.

My rear shocks are KONIs (4th Gen, SA) and I have no issues or scraping over bumps, in hard corners, getting the car sideways in a turn, or other aggressive street driving (on typical crappy, half-assed repaired streets).
However, I removed my back seats and have no plans on carrying rear passengers.

 

I'm going to get some better shocks some new bump stops and rear control arm bushings and see what happens

 

I don't know what spring rate you have in back (110lb?), but increasing it to 150lb/in combined with good shocks really helps prevent bottoming out. Are you lowered at all?