I been searching for a while and i'm getting mixed results. I need to know what the best backspacing would be for a 15x8 rim for the rear of the car. I dont want to modify anything. 5.5 or 4.5 backspacing ?

what size tire?

both you mentioned would work, one would just sit in a little more than the other

I hear a 275/60/15 is good but i will use what ever sits in the wheel wells nice with out hammer the crap out of the car.

5.5 will work good with 275/60/15. I have 15x9 with 5.5 with those size tires.

Theres no difference between a 15x8 and a 15x9 rim ?

one is an inch wider

I firgured that out I'm just saying that with that extra inch the 5.5 backspacing would stil move the rim. So im just making sure that a 15x8 with say a 275/60/15 tire would still work without any mods.

On the rear of my 84Z I have 15x8 rally wheels with 4 inch backspacing and 275/60 BFGoodrich TA radials. They stick out just a bit too far and I rolled the wheel lip for extra clearance. 4.5 backspace should be fine. I know an earlier post said 5.5 would work but on my car I just don't see that there would be enough clearance.

Hope this helps.
Mike

I got 15x8 cragars all the way round > No backspacing needed at all & tires sit well in the fender...Bigger pics in my profile/Album if you want to check to see how mine fit...

backspacing is the distance from the hub to the back edge of the wheel...
just to be clear...
it has nothing to do with banging a hammer in your wheel wells.

Duh! You quoted me and the next guy... Mine fit great and no hammering needed.... Pay attention! DUH!!!!!

Every wheel has a backspacing....it's a measured distance....you have to have backspacing, if you had no backspacing then the bolt flange would be even with the edge/lip of wheel and look really stupid, let alone not fit.
Your probably thinking of wheel spacers.
DUH!!!

Thanks for the update .... REREAD ALL POST..No Back-spacing/wheel spacing MY 15x8 fit great! I guess if you could afford Cragars you would understand stand no MODS are needed >>>>

what we are saying is that backspacing is a property of the wheel. cragars or not, every wheel has backspacing. its a physical property of the wheel itself.
oh, and cragars arent really that great.
as for no mods being needed, ok, thats different, and yes, its true.



to the OP, generally speaking, try and keep the backspacing proportional to rim width.
what i mean is this:
say you start with a 7" wide wheel with 3" backspacing.
if you move to a 8" wide wheel, you will want between 3.5" and 4" of backspacing.
the idea is to keep the "front spacing" the same.
7-3=4" of front spacing.
8-4=4" of front spacing.
there is some room for leeway here of course.
if you want the wheels to stick out more, then go with less backspacing.
there is not a simple "BEST" fit

Wow, I really did a bad job trying to help out. All I said in my original post was my rims(15x8) fit fine >>> Backspacing/spacers was never a concern for me !!! Talk about being thrown under the bus!

no body was throwing you under the bus, they were just trying to correct a misstatement of terminology, and then a yelling match started over misinformation. I think its been cleared up now, but i cant tell what is sarcasm in your post and what isnt.

Im sure your wheels fit fine, but they still have backspacing. Backspacing and spacers are not the same thing. Spacers are used when the wheel you are suing has too much backspacing, ie, 4th gen wheels. Backspacing is just the distance from the mounting surface of the wheel to the inner edge. Every wheel has backspacing, i have never seen a wheel of any size that has 0 backspacing, except maybe a bicycle wheel.

for the OP, a 15x8 with anywhere from 4.5 to 5.5" of bs will bolt on fine. 5 would probably be ideal to center the tire in the wheel well.

right idea, but not correct. The width of a wheel is measured form the inside of the bead seats. So a 15x8 wheel will actually measure about 9" wide. a 15x9 will measure 10" wide, ect. the diameter is measured the same way, so a 15" wheel will measure almost 16" in diameter if measuring to the outermost end of the lip as opposed to the bead seat.

But either way that extra half inch was there to begin with and is there after you change wheels so it cancels out in the end...

It would be different if he was installing 12" wide wheels but with 8" wheels it's not a concern.

I think you are thinking of ZERO OFFSET which if that's the case then you are correct....that means the bolt hub is in the center of wheel....maybe confused about the different terms?

i understand that, and the backspacing is still measured to the outermost edge of the wheel, i just thought i would through that little tidbit of info out there because its important to know how to measure the wheels.