69 15x8 backspacing - Impala Tech
Wheels & Tires What fits?

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post #1 of 11 (permalink) Old 01-14-2020, 04:08 PM Thread Starter
 
 
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69 15x8 backspacing

I'm wanting to order a set of torque thrust style 15x8 wheels this week and run 255/60/15 tires all around if possible. 4.75 backspacing and neutral offset is the set I found, curious if anyone has tried this much offset on a 67-70 impala/full size and had any insight? It's a 327 SB if that matters suspension wise. Thank you!

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post #2 of 11 (permalink) Old 01-15-2020, 09:09 AM
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Should be ok with Neutral backspacing.

I am going to run 15x8 steels, Backspacing 4.250 in. Offset:-6mm on all 4 and the only issue I've ran into so far is that the steel wheels don't clear C3 Corvette front Disk brake calipers.

So your wheels would be about 1/2" further out from the hub. Guess it depends on what tire you plan on using. The pictures below are the 15x8" with a 245/60R15 Tire. 26.5" tall and about 9.5" wide.

the pictures below are with a Standard Drum brake setup on stock suspension:








Ted

Last edited by brickwhite; 01-15-2020 at 09:35 AM.
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post #3 of 11 (permalink) Old 01-15-2020, 09:34 AM
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The fit on a 69 is a little different from earlier years. Easiest thing to do is get the car up on stands and take careful measurements to be sure. The rear axle can be "off center" by as much as 1/2" from the factory.

A 69 Impala will easily clear a 10" wide rim with the proper back spacing with about 1/2" - 3/4" clearance on the frame and fender. I have 285/35/R19 tires on the rear and 245/40/R18 tires on the front with zero issues and no clearancing or fender rolling. This is with the car sitting about 1" lower in the rear and 2" lower in the front.

When I get the body off I'll be able to shave a bump on the frame and fit 300's on the rear easy.

1969 Impala convertible build thread here:
https://www.pro-touring.com/threads/...ghlight=impala
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post #4 of 11 (permalink) Old 01-15-2020, 10:34 AM Thread Starter
 
 
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Awesome! What exactly is considered neutral backspacing on these cars? The rims I was looking at are actually 4.5 back space and 1mm offset, I was thinking of running Cooper Cobra radials in 255/60/15. Those tires look nice on your ride!

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post #5 of 11 (permalink) Old 01-15-2020, 10:39 AM Thread Starter
 
 
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Quote:
Originally Posted by justjohn View Post
The fit on a 69 is a little different from earlier years. Easiest thing to do is get the car up on stands and take careful measurements to be sure. The rear axle can be "off center" by as much as 1/2" from the factory.

A 69 Impala will easily clear a 10" wide rim with the proper back spacing with about 1/2" - 3/4" clearance on the frame and fender. I have 285/35/R19 tires on the rear and 245/40/R18 tires on the front with zero issues and no clearancing or fender rolling. This is with the car sitting about 1" lower in the rear and 2" lower in the front.

When I get the body off I'll be able to shave a bump on the frame and fit 300's on the rear easy.
That's where I'm at now too, that'll be the next move, definitely only want to order once and have it fit right, what backspacing and offset are your wheels?

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post #6 of 11 (permalink) Old 01-15-2020, 11:07 AM
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Pretty sure neutral backspacing means the wheel is almost centered on the hub or would have 1mm to the front for your specs.

EX. 8" wheel would have almost 4" front of the hub and 4" back of the hub or something like that.


Ted
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post #7 of 11 (permalink) Old 01-15-2020, 02:07 PM
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Quote:
Originally Posted by foggymug View Post
That's where I'm at now too, that'll be the next move, definitely only want to order once and have it fit right, what backspacing and offset are your wheels?

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I'm using stock C6 Corvette wheels with 2.375" front adapters and 3" read adapters, 1/2" studs on everything.

Stock Corvette sizes are:
Size / Offset / Back Space
Front 18x 8.5 (+) 56mm 6.45
Rear 19x 10 (+) 79mm 8.1

1969 Impala convertible build thread here:
https://www.pro-touring.com/threads/...ghlight=impala
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post #8 of 11 (permalink) Old 01-15-2020, 03:04 PM Thread Starter
 
 
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Quote:
Originally Posted by brickwhite View Post
Pretty sure neutral backspacing means the wheel is almost centered on the hub or would have 1mm to the front for your specs.

EX. 8" wheel would have almost 4" front of the hub and 4" back of the hub or something like that.

Ahhh okay that actually makes sense, thank you for that! I'll measure it out one of these days but it's sounding like 4.5 backspacing on an 8inch rim will fit just right with the 255/60/15, anything to get rid of these shoe strings haha

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post #9 of 11 (permalink) Old 01-15-2020, 03:05 PM Thread Starter
 
 
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Quote:
Originally Posted by justjohn View Post
I'm using stock C6 Corvette wheels with 2.375" front adapters and 3" read adapters, 1/2" studs on everything.



Stock Corvette sizes are:

Size / Offset / Back Space

Front 18x 8.5 (+) 56mm 6.45

Rear 19x 10 (+) 79mm 8.1
Sounds awesome! Any photos?

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post #10 of 11 (permalink) Old 01-16-2020, 03:21 PM
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Originally Posted by foggymug View Post
Sounds awesome! Any photos?

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The build thread is in my signature. These are from the 2019 Power Tour:
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1969 Impala convertible build thread here:
https://www.pro-touring.com/threads/...ghlight=impala
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post #11 of 11 (permalink) Old 01-16-2020, 03:48 PM
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Originally Posted by brickwhite View Post
Pretty sure neutral backspacing means the wheel is almost centered on the hub or would have 1mm to the front for your specs.

EX. 8" wheel would have almost 4" front of the hub and 4" back of the hub or something like that.

That picture is about half right. The correct part is that neutral offset or 0 offset means the wheel is centered on the hub.
The wrong part is the width of the wheel and the way they are calculating backspacing.

7" wide wheel (advertised) is 8" wide (actual). Advertised width is bead to bead but actual width measured from lip to lip.
This is why 7" wide wheel that's 0 offset would have 4" backspacing, not 3.5" as in the picture.

For example 15x8" is 9" wide, 9" divided by 2 is 4.5" backspacing which equals 0 offset.

10" wide wheel is actually 11" wide, so 11 divided by 2 = 5.5" backspacing = 0 offset

I hope this makes sense.

As long as you keep close to 0 offset, wheels will fit. You can probably run 275/60 on the back without issues. on my 67 I have corvette rallies which are 15X8 but 4" backspacing (not 0 offset, 1/2" more towards the fender) and 275/60 fits perfect.
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