Backspacing

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For $350, I think I could find a set of 15" tires that I would be happy with.

Very well done.

 
Pics as promised.

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Front

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Rear

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Thanks for looking and the info.

 
Thanks guys, the wheels are in better condition than I thought before I went and saw them. They are defiantly worth the price I paid for them, in my opinion.

 
i was going to say if a 15x8.5 with a 4.5 BS won't fit then how in the world am i fitting a 17x11 with a 7BS and a 315 wide tire in my mach?!?!?!?!

i do however have the fender wells rolled and the tires i run are only 26 inches tall but 14 inches wide

 
i was going to say if a 15x8.5 with a 4.5 BS won't fit then how in the world am i fitting a 17x11 with a 7BS and a 315 wide tire in my mach?!?!?!?!

i do however have the fender wells rolled and the tires i run are only 26 inches tall but 14 inches wide
These are actually 3.75" backspacing, a 4.5" BS would be quite similar to the factory offset.

 
they look awsome. Could probably stand to be maybe 1/2" in, but they give the car that oldschool tough look...

Just to confirm (collecting datapoints):

- you're sure that they're 8.5" rims, with 3.75" BS (1" offset out)?

- those are the 245 60 15's you mentioned earlier?

i was going to say if a 15x8.5 with a 4.5 BS won't fit then how in the world am i fitting a 17x11 with a 7BS and a 315 wide tire in my mach?!?!?!?!

i do however have the fender wells rolled and the tires i run are only 26 inches tall but 14 inches wide
do you have pics/details up somewhere? your tires should be a little over 12" wide... not much out there is 14"...

I suspect that if anything you have interference issues on the inside of your wheel wells (your 7"BS ends up with the tire offset 1" to the inside of the hub mounting surface), where he should have tons of room on the inside, and was worried about contacting on the outside/lip because his wheels are offset 1" to the outside (his tire centerline ends up 2" further out than yours), which assuming a normal spec tire in the sizes both of you listed (and the BFG's tend to run a little wider), the outer edge of his tires should be roughly 3/4" out farther than yours (actually .62", but he's running the tire on a proportionately wider rim for the size than you are so they'll add a little to the sidewall).

 
they look awsome. Could probably stand to be maybe 1/2" in, but they give the car that oldschool tough look...

Just to confirm (collecting datapoints):

- you're sure that they're 8.5" rims, with 3.75" BS (1" offset out)?

- those are the 245 60 15's you mentioned earlier?
I'm 95%, I'm going to put my old wheels on while I do some welding and what not, I'll confirm then. Yep they are wrapped in 245/60r15 BFG Radial T/As. If I'm not mistaken a 3.75 BS on a 8.5" wheel would give you -25 offset.

 
the BS is measured from the outside edge of the lip to the back of the mounting flange, the width is measured from inside edge of the lip to inside edge. Most aluminum rims have roughly a 1/2" thick lip, so an 8.5" wheel will actually be 9.5" from the outside edge to outside edge of the wheel lip.

SO

if it's really an 8.5" rim, then it's going to measure 9.5" wide with a 4.75" centerline and a 3.75" BS, that means that you'll have 1" offset out (I prefer to use in and out rather than + and -, because what wheel manufacturers call + and - is reversed from what is used in a lot of chassis engineering books and it can be confusing). I do wonder if you really have an 8" rim, since that would be a more common size, and I'm also suprised that a 1" offset rim clears the fender lips well enough with a tire that wide.

That said, I'm asking you to confirm all these numbers since if you do you could be providing us the best data points WRT to what will fit that I've seen yet. I can calculate where the outside surface of your tire bulge is within about .1", and based on your picture I would guess that what most people would call a _perfect_ fit would be with that edge .25-.5" in from where you have them now (I think that most people would say that your tires stick out _a little_ but they more than close enough for 90% of people). Based on that and a little math I can calculate the offset or backspacing that you'd need to tuck just about any tire in that can possibly fit in the wheel well (well, with a little bit of allowance for height, but since your 245's are around 26.5" tall, taller than most normal tires you've even accounted for that).

BTW, usually at least the rim width is cast into the back of the rim (the offset is usually not because the final setting is determined by machining)

BTW2, depending on the hub thickness and they type of lug seats, if you're ambitious you might be able to machine the hubs down enough to get the rims to tuck at least another .25" in, maybe more. Typically if they're machined for washer seat lugs and have a thick hub you can make a lot of change without weakening the rim, tapered seat lugs not so much so.

xoliex- again, I'd like to see pics of your car and any more details you can give, that should confirm my math and his numbers.



I don't know if this will help you, but I'm running 15x8 American racing 200s on the rear with a 4.75 backspacing and I do have to use air shocks to keep the body off the sidewalls.

The wheels your considering do look really sweet! I've always liked the look of the "Slots"! ::thumb::
QCode... I found these pics of your car (I love daisy mags, beautiful car, sweet stance):

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What size are those back tires? Do the outer fender lips tend to touch or are you hitting on the inside somewhere without the air shocks?

What's your front tire and wheel size/offset???

This one would also be very helpful in figuring this out, especially since you seem to have a very nice fit with a great stance and largish tires.


I'll try to pull the rims that came on mine off also and do some measuring (I think they're a set of old school centerline Champ 500's, but they're missing caps...), but they're not really big enough to get really good numbers off of (I think they're 15x7 with 235 60 15's on all 4, they look just slightly better stance wise than a set of stockers. Honestly, I'd probably be OK with them if I could find a matching set of 15x10 or at least 15x8.5 for the back, they have just enough old school cool for me to deal with them. Not as nice as a set of Daisies or Jellybeans... interestingly my tires are seriously rotted but hold air fine... I guess that's par for the course for this car.

 
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I didn't forget about you Silverback, just been busy lately I'll let you know soon about the measurements.

 
Hey Silverback, I finally confirmed the measurements of my wheels. They are 15x8.5 with a 3.50" back space, which I thought was 3.75" but I must have misremembered the number.

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Thanks for being patient with me.

 
I guess after not seeing anything for over a month I lost track of this thread... I suddenly found it going though my PM's.  :whistling:

I just re-read the whole thing because I still think that there is good info to be had here, but ended up confused:  

- You started saying that they were 8.5" (which you confirmed with the casting mark) with 4" BS

- then you measured with a plumb bob and it looks like you got 5.5" to the hub on the front and 5" on the back (I'm guessing this is from the edge of the tire bulge, and I'm guessing that you'll measure .5" from the bulge to the lip), that would mean you have pretty close to 4.5" BS (.5" or 13mm offset out),

- but then we started talking about 3.75" offset (I read through this thread 2x and can't figure out where that came from)

- and finally you said you confirmed they were 3.5" backspacing (I don't know how, that wouldn't workout with your plumb bob measurements at all.

Can you, if you're still even around, confirm what it is?

I love how they look with the 245's, but that is not a size I would run on the back of my car... I'd like to get more meat back there and tuck the tires a little more.  I have my thoughts of what I would do if they were mine to get something like a 295/60 on them (and it's likely that there are others like them out there with that offset/backspacing if we can confirm what that is), but I don't want to get too much into that till I know what they are (believe me, it would be cool) 

:cool:

 
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