Jody [/qb][/QUOTE]Jody you are incorrect, 5" backspacing put the wheel dangeriously close to the inner well and shock, 4" places the 8" wheel dead center in the wheel well between the front lip and the inner well wall. You are telling us 5" bs barely cleared the outer wheel well, that is nuts when there are tons of people on this board running 4.5 and 4" backspacing on an 15x8 rim without any problems.
ChevyHP says the max you can get is
15 inch wheel, 4.87 backspace, 8.5in width, 28X10.5 tire, so if you shrink the wheel down to 8" rim size then to keep the wheel centered as ChevyHP recommends you would use a 4.38" backspacing, or to keep the outer rim lip the same as ChevyHP recommends but give yourself a little more inner well clearance you would use a 4" backspacing. [/QB][/QUOTE]
No way. I was there, believe me. Been there, done that. A 4.5" might work but NO WAY 4" on an 8" rim with 275/60's will clear on anything stock height or (especially) lowered. It was close on the inside, but even that far in we still had to roll the outer wheelwells completely under (which the owner did NOT want to do) to gain clearance. He started with the standard offset 15X8" which came with 3.75" b.s. The tire sidewall was even with the OUTSIDE of the wheelwell; how can 1/4" further in make it work? And yes, he had this setup on the stock 10 bolt and the stock 12-bolt from my yellow car, so the rear end width was factory.
Yes, you can run a 15X8" wheel and 4" b.s. on the rear, just not with a 275/60-15 tire, UNLESS your car sits higher than stock and has air shocks to prevent it from dropping at all.
Using your theory of an 8" wheel needing a 4" b.s. to be centered in the wheelwell, then a 17X9.5" wheel should use a 4.75" b.s. to fit correctly in the center, right? That combo requires a 5.5" b.s. to work, almost an inch more b.s. from centered which is what my recommendation of 4.75" to 5" is.
For a 4" b.s. on an 8" wheel to be centered in the wheelwell as you say, then the flange the wheel bolts onto on the rear end must also be centered in the wheelwell. It is not; it is closer to the outer wheelwell than the inner wheelwell by nearly an inch, hence the need for more backspacing. All of this depends on the tire size though; if the tire is small enough you can get away with a 3.75" to 4" b.s. on an 8" wheel. But not when you're trying to fit something as large as a 275/60.
[ 04-21-2004, 09:16 PM: Message edited by: Camcojb ]