#1  
Old 05-01-2021, 08:40 AM
djustice's Avatar
djustice djustice is offline
Senior Member
 
Join Date: Jan 2014
Location: Norway
Posts: 238
Default strange offset. need input

I am trying to figure out my backspace/ET of my current rear wheels. it looks as if it is American racing outlaw 1 in 15x8 spec. link: https://www.americanracing.com/produ...ar61-outlaw-i/
The wheels are a 100% identical centercap says american eagle insted of american racing, there migth have been a company named american eagle producing copys as the centerline design have been quite popular.

Now the website states that it is 3.75 backspace (ET -19 mm)
I have measured mine and i am at loss as they are stamped with 5x4.75, 15x8
no ET/offset is stamped on them. But when i measure i come up with 3.3"
translates to ET -30


Picture of my measure method:

For my sanity, i need someone to comfirm that my measurement is correct or in-correct.

__________________
Murphy's law - "Anything that can go wrong will go wrong".
-469 ,Butler 310+ Eheads, Hurricane intake portmatched by butler, Butler roller 230/236 @0.50 112 LSA, Johnson lifters, pypes 2 1/2" exhaust, 3.42 yukon duragrip lsd, holley sniper efi, hyperfuel efi tank +++

Last edited by djustice; 05-01-2021 at 09:38 AM. Reason: typo (there migth be more :)
  #2  
Old 05-01-2021, 09:27 AM
amcmike's Avatar
amcmike amcmike is offline
Ultimate Warrior
 
Join Date: Oct 2004
Posts: 1,733
Default

Looks like you're doing it right. Appears you have the straight edge right on the absolute outside of the rim going to the pad which is how backspace is defined.

Offset is measured to relative to the inside of the rim lip (which is how manufacturers define the rim size). So if the rim is stamped 15x8 it should measure 9" to the outside dimensions. Therefore zero offset would be 4.5" backspace. At 3 5/16" (3.5125") you're difference to zero offset is -1.1875"=-30.1625mm



http://www.gtsparkplugs.com/Backspac...alculator.html

__________________
"The Mustang's front end is problematic... get yourself a Firebird." - Red Forman
  #3  
Old 05-01-2021, 09:35 AM
djustice's Avatar
djustice djustice is offline
Senior Member
 
Join Date: Jan 2014
Location: Norway
Posts: 238
Default

Thank you! i have been trying to do some research using wayback machine internet archives and have found a site called american eagle alloys active to about 2002 , but there is very little info preserved in the archive, but the logo looks identical to my centercap, so they migth actually be american eagle alloy that migth have a different offset than American racing outalw 1.

__________________
Murphy's law - "Anything that can go wrong will go wrong".
-469 ,Butler 310+ Eheads, Hurricane intake portmatched by butler, Butler roller 230/236 @0.50 112 LSA, Johnson lifters, pypes 2 1/2" exhaust, 3.42 yukon duragrip lsd, holley sniper efi, hyperfuel efi tank +++
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 02:45 AM.

 

About Us

The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.

 




Copyright © 2017