Backspacing and Offset

J

jonnyslick

G-Body Guru
Jun 2, 2008
699
0
Crossville, TN
No matter how many times I try to get this, I never can seem to get my mind around it.

Are backspacing and offset dependent on each other, or independent?

For instance .. if you have two 15x8 rims with a 5 inch B.S. will the offset on both of the be the same, or is it possible to have a two 15x8 inch rims, each with a 5 inch B.S. but with DIFFERENT offsets?

The reason I'm asking is b/c I'm looking at some custom rims, but that only list offsets (not B.S.) .. so if offsets and backspacing are dependent on each other, then I can easily figure out which will fit and which won't. If they're independent, then I don't know how to gague if the rim will fit w/o physically having the rim to measure.
 
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megaladon6

megaladon6

Comic Book Super Hero
May 29, 2006
4,054
0
Danbury, CT
http://www.rims-n-tires.com/rt_specs.jsp
basically, backspacing is the distance from the mounting flange of the rim to a line flush with the inside edge of the rim. the question is the lip of the rim. some places measure it and some don't.
offset is the distance from the mounting flange of the rim to the centerline of the rim.
 
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GP403

GP403

Administrator
Site Admin
Moderator
Feb 25, 2005
3,386
113
Inola, OK
Moved and stickified, thanks for the link.
 
megaladon6

megaladon6

Comic Book Super Hero
May 29, 2006
4,054
0
Danbury, CT
no problem. i love playing around with different combo's on there. so much more interesting than TV. :lol:
for some more measuring stuff (and they seem to be one of the best companies for adaptors)
http://www.skulte.com/adapterfaq.html
 
turbo78

turbo78

Greasemonkey
Nov 1, 2009
224
0
billings, montana
yea ya know i dont understand why some companies decided they needed to change things up and throw everyone for a loop, backspace has always been how to order wheels, but offset was some import ****er's idea to be different... :blam:
 
megaladon6

megaladon6

Comic Book Super Hero
May 29, 2006
4,054
0
Danbury, CT
i think it's america vs europe again, but that's a WAG.
technically speaking going by offset may be the better way because the wheel should be centered on the bearing/load bearing part. therefore with offset you know which way and how much the wheel is shifted off center. but that's also a SWAG.
 
G_Body_Enthusiast

G_Body_Enthusiast

Royal Smart Person
Supporting Member
Feb 28, 2005
1,065
38
Louisville, kentucky
turbo78 said:
yea ya know i dont understand why some companies decided they needed to change things up and throw everyone for a loop, backspace has always been how to order wheels, but offset was some import ****er's idea to be different... :blam:
actually offset is important, when you turn your steering wheel your tires turn giving you the scrub area. you want the scrub area centered in the tread, not off to the outside or inside too much. a well centered tire wears better than one with a bad scrub center. it also helps with handling.

it's just import guys tended to care more about this since they cared about handling and most guys with american cars for decades didnt care how their car handled, NOW we do so now we're seeing offset numbers for all kinds of wheels for our cars.
 
P

Phil

Not-quite-so-new-guy
May 9, 2010
26
0
Iowa
Im looking into this also, What is the Stock BS for a Monte car anyway? That might help me find something, I want something close to stock..



Thanks
-Phil
 
383Camino

383Camino

Master Mechanic
Mar 1, 2006
265
16
South Dakota
Instead of worrying about offset, can't we just look at the BS and width? Won't that effectively take care of the offset woes as well?

I fit wheels and tires based on backspacing, casue thats where the wheel actually sits on the car.
 
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