Will they fit well on a 92 firebird? Theyre 5x4.75 x 9 I think...

 

size/width/backspacing?

what year C5 or C6 Z06 wheels?

 

if they are 9 or 9.5 wide in 17-19 2 inch all around will work, wider wheels will need wider adapter, inner fender work and possible suspension rubbing. it all depends on wheel and tire size mounted on that wheel

 

My 18x9.5 and 18.8.5 c6s bolted right up with a 2" spacer
Running 275/35/ZR18s and only have rubbing on the inner fender well at full lock, rear is fine.

My friend's had 17x9.5 c5 z06s (cant remember tire sizes) and had no rubbing with 2" spacers

 

Need help to I got 89' IROC with 09 z06 rims 345/30-19 on the rear....what size spacer will I need...or are they to wide...don't want to do any fad to rear of car...just spacers...

 

Like I said for your other post, you more than likely won't fit that wide of wheel/tire in the back with just a spacer. You COULD, but you would have enough spacer that your tires would stick atleast an inch outside the fenders. It also isn't safe to have 3+" of spacers as it puts too much load on the studs.