Wheels & Tires Forged | Billet | Cast | Radials | Slicks

Custom wheel, OEM backspacing?

Thread Tools
 
Search this Thread
 
Old Aug 29, 2010 | 07:04 PM
  #1  
Element's Avatar
Thread Starter
TECH Fanatic
iTrader: (5)
 
Joined: Jan 2006
Posts: 1,575
Likes: 2
From: WV
Default Custom wheel, OEM backspacing?

Just curious, when ordering a custom wheel, is there any reason (for a Trans Am) to order something other than the 7" backspacing/50mm offset for the front and rear?

Going to be picking up a set of Billet Specialties 17" RTs over the winter, and just want to make sure I get the numbers right.
Reply
Old Aug 30, 2010 | 04:38 PM
  #2  
Element's Avatar
Thread Starter
TECH Fanatic
iTrader: (5)
 
Joined: Jan 2006
Posts: 1,575
Likes: 2
From: WV
Default

Damn, nothing?
Reply
Old Aug 30, 2010 | 11:41 PM
  #3  
99Bluz28's Avatar
TECH Senior Member
iTrader: (35)
 
Joined: Nov 2007
Posts: 9,705
Likes: 12
From: C. V., Kalifornia
Default

How wide are the wheels your getting?
Reply
Old Aug 31, 2010 | 07:12 AM
  #4  
Element's Avatar
Thread Starter
TECH Fanatic
iTrader: (5)
 
Joined: Jan 2006
Posts: 1,575
Likes: 2
From: WV
Default

Originally Posted by 99Bluz28
How wide are the wheels your getting?
17x11 in the rear, 17x9.5 in the front.
Reply
Old Aug 31, 2010 | 12:52 PM
  #5  
99Bluz28's Avatar
TECH Senior Member
iTrader: (35)
 
Joined: Nov 2007
Posts: 9,705
Likes: 12
From: C. V., Kalifornia
Default

About a +45mm offset for the 17 x 11's in the rear, and a +45 to +38mm offset for the 17 x9.5's up front.

17 x 11's: 7.75" BS .

17 x 9.5's: 6.75" BS(+38), or 7" BS(+45) .

For BS you need to know the overall wheel width, I figured it as 1" wider then the stated wheel size, this is an average, your's might be more or less.
12" for the 11" wheels , and 10.5" for the 9.5" wheels. So unless you know the overall wheel widths go by the offset numbers , not the BS numbers.
Reply
Old Aug 31, 2010 | 01:40 PM
  #6  
Element's Avatar
Thread Starter
TECH Fanatic
iTrader: (5)
 
Joined: Jan 2006
Posts: 1,575
Likes: 2
From: WV
Default

Ok...wasn't quite sure if the numbers in the sticky were more of a "These wheels come with x, xx, and xxx offset, use xx for best results" sort of thing, or if they were pretty much spot-on.

Stupid question since I've never ordered wheels before, but if I know the offset I want, do I just call the manufacturer up and say, "17x11s for a '99 Trans Am, +45mm offset." and they take care of the backspacing conversion and everything else required?
Reply
Old Aug 31, 2010 | 02:13 PM
  #7  
99Bluz28's Avatar
TECH Senior Member
iTrader: (35)
 
Joined: Nov 2007
Posts: 9,705
Likes: 12
From: C. V., Kalifornia
Default

Originally Posted by Element
Ok...wasn't quite sure if the numbers in the sticky were more of a "These wheels come with x, xx, and xxx offset, use xx for best results" sort of thing, or if they were pretty much spot-on.

Stupid question since I've never ordered wheels before, but if I know the offset I want, do I just call the manufacturer up and say, "17x11s for a '99 Trans Am, +45mm offset." and they take care of the backspacing conversion and everything else required?
You'll need to find out what offsets they offer, if they don't offer those exact offsets, then get it a close as you can with what they offer.
Also find out what BS they offer, and if possible what there overall wheel widths are for the 17 x 9.5's and 17 x 11's. The post it up here, then I could give you a accurate BS numbers.
Reply
Old Aug 31, 2010 | 02:35 PM
  #8  
Element's Avatar
Thread Starter
TECH Fanatic
iTrader: (5)
 
Joined: Jan 2006
Posts: 1,575
Likes: 2
From: WV
Default

Originally Posted by 99Bluz28
You'll need to find out what offsets they offer, if they don't offer those exact offsets, then get it a close as you can with what they offer.
Also find out what BS they offer, and if possible what there overall wheel widths are for the 17 x 9.5's and 17 x 11's. The post it up here, then I could give you a accurate BS numbers.
They don't call out specific offsets; rather, a range of backspacing offered for each wheel. Their page is somewhat short on info (the linked catalog page doesn't even show the RTs in anything other than 15" sizes) and only lists the wheels as 17x9.5/17x11, with available backspacing of 3.5" to 7.25" and 3.5" to 8.5", respectively.
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-1

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-2

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-3

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-4

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-5

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-6

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
story-7

Awesome K5 Blazer Restomod Comes With C7 Corvette Power

 Verdad Gallardo
story-8

10 Camaros You Should Never Buy

 
story-9

10 LS Engine Myths That Refuse to Die

 Verdad Gallardo
Old Aug 31, 2010 | 02:59 PM
  #9  
99Bluz28's Avatar
TECH Senior Member
iTrader: (35)
 
Joined: Nov 2007
Posts: 9,705
Likes: 12
From: C. V., Kalifornia
Default

Originally Posted by Element
They don't call out specific offsets; rather, a range of backspacing offered for each wheel. Their page is somewhat short on info (the linked catalog page doesn't even show the RTs in anything other than 15" sizes) and only lists the wheels as 17x9.5/17x11, with available backspacing of 3.5" to 7.25" and 3.5" to 8.5", respectively.
Those Back Spacing numbers I posted should be really close, I'd go with those unless Billet Specialties has good reason for you to go with a different Back Spacing #s. Up front it's up to you, if you want the wheel/tire in(7"bs) or out(6.75"bs) a little more.
Reply
Old Aug 31, 2010 | 03:02 PM
  #10  
Element's Avatar
Thread Starter
TECH Fanatic
iTrader: (5)
 
Joined: Jan 2006
Posts: 1,575
Likes: 2
From: WV
Default

Originally Posted by 99Bluz28
Those Back Spacing numbers I posted should be really close, I'd go with those unless Billet Specialties has good reason for you to go with a different Back Spacing #s. Up front it's up to you, if you want the wheel/tire in(7"bs) or out(6.75"bs) a little more.
Sounds good. I just wanted a rough working number for when I call to order the wheels, to at least have some idea of what I'd need.

Thanks for the help.
Reply




All times are GMT -5. The time now is 12:03 PM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE