I have a 1983 Z28 & looking at Weld Prostar 15 x 9's with 5.5" backspace & 275/60 R15's. I don't want to modify wheel wells. Does anybody have this combination? Any Pics?

 

Should be able to fit a 15x10 on the back with 5.5 backspacing. I am not 100% sure but I think it will fit.

 

If this helps you, then I have 275/60 R15's on the stock 20 slot rims on my 84 TA. IIRC, those rims are 15x8.
I believe those rims have 5.5" backspacing, not completely sure. But the right tire rubbed on the inside when accelerating around a RH turn. I fixed that by using 3/4" wheel spacers with longer wheel studs on both sides.

 

Thanks to both for your reply. I am looking to put the 15 x 9 Prostars on the rear, with 15 x 5 Prostars on the front. NoEmissions, I assume the rubbing you had was on the front, am I correct? I see you have a 10 bolt rear with the Auburn Posi. Is that the original 10 bolt rear (I believe 7 1/2")? I am looking at a Moser 12 bolt for my car, but very expensive. I also looked at beefing up the original 10 bolt, but have heard different opinions on doing that. I plan on changing the 305 to a 350.

 

Don't put money into the 10 bolt. It's just not worth it.

Cheapest way to go is still a Moser 9" housing and axle package and a junkyard center chunk

 

Correct, 7.5" 10 bolt stock rear. My rubbing was on the inside of the rear tires, probably towards the front. If I got on it in a RH turn, when the trans upshifted into 2nd, I got a "bark" from the PASS rear 275/60/15 TA radial rubbing on the inside wheel well. I made 3/4" aluminum spacers for both rear wheels with longer studs. Problem solved.

How much power are you planning to make that you NEED the 12 bolt?