[Chevelle-list] First tire/wheel thread of the New Year!

[Dale]

Backspacing and offset are directly related.  A 15x8 w/4.5" of backspacing
has 0" offset.  If you increase (+) or decrease (-) the offset, you increase
or decrease backspacing.

Offset ~ The offset of the wheel is the distance from the mounting pad to
the centerline of the wheel.

Backspacing ~ The measurement from the mounting pad to the inner edge of the
wheel.

They are two different terms, just measured differently and different wheel
mfgs will use one measurement or the other.  On a 8" wide rim (9" at the
bead) if you offset the mounting flange +.5" you get a 5" backspace.
Consequently if you offset the flange -.5" you get 4" backspace.  You can't
increase/decrease one without increasing/decreasing the other.

See http://www.chevellestuff.com/tech/wheel_offset.htm for a more detailed
explanation.

I have the American Racing Outlaw I 15x8s on my 67 El Camino and ran the
same wheels for years (from 87 to 01) on my 67 SS Chevelle.  I run 15x8 with
235/60 on the rear and 15x7 with 215/60 on the front.  I could probably run
a wee bit wider tire on the rear and still have clearance but I sometimes
get heavy loads in the car and don't want to push it.

Wheels on the Elky: http://dalesplace.com/htm/camino/our_camino_main.htm
Wheels on the Chevelle: http://dalesplace.com/htm/chevelle/how_it_was.htm


ARE's Truck/SUV designation is their category for listing purposes since
they are popular with the pickup crowd.  Since these Outlaw I's have a
negative offset of -19mm it results in less backspace (or backside) since
the mounting flange is moved towards the car side of the wheel and they
generally need more open-style wheel wells than our Chevelles allow.
They'll fit but limit the size/ratio tire that can safely be run.  Their
specs show -19mm offset and 3 3/4 backside (backspacing).  
8" wheel is 9" at bead
9 / 2 = 4 1/2" center w/0" offset
-19mm (3/4") negative offset means less backspace; 4 1/2" - 3/4" = 3 3/4"
backspacing.

If you want offset/backspacing special, you'll need to pay for that.

Dale McIntosh
1966/67 Chevelle Reference CDs
ACES #1709/TC GOLD #92
 
-----Original Message-----
From: chevelle-list-bounces at chevelles.net
[mailto:chevelle-list-bounces at chevelles.net] On Behalf Of John Nasta
Sent: Monday, January 01, 2007 11:00 AM
To: Chevelle-list at chevelles.net
Subject: [Chevelle-list] First tire/wheel thread of the New Year!

Hey everybody,

I think I found the wheels I want for my '70 Malibu (American Racing  
Outlaw I):

http://www.tiresdelivered.com/proddetail.php?prod=61-5861

Seems to me that everybody here has said to go w/ 15x8's w/ 4.5"  
backspacing, but I don't know what offset is recommended if any.

I really wanted Centerline Autodrags but of course they are two and a  
half times the price. Centerline doesn't list the Auto Drags as a 15x8  
w/ 4.5" back space. The closest is 15x8.5 w/ 4-7/8" backspacing.

Anyway, the American Racing web site lists this wheel as a SUV/Truck  
application and shows 5x4.75 bolt pattern 15x8's only available in -19  
offset w/ 3.75" backspacing, which I don't think would work for me. Am  
I stuck with having to spring for Centerlines if I want that look?

I also have a pair of 15" wheels that look like the American Racing  
Outlaw II or Centerline Convo that I will be selling once I have a new  
set. I don't know what brand they are or what the backspacing is, but  
I'll check them out if anyone is interested.

Happy New Year,
John Nasta