Wheel Dimensions


Wwabbit

GT Owner
Mar 21, 2012
1,259
Knoxville, TN
Thanks for the question. I learned something - again.
 

Fubar

Totally ****** Up
Mark II Lifetime
Le Mans 2010 Supporter
Aug 2, 2006
3,979
Dallas, TX
Does anybody know the wheel dimensions and offset measurements for the stock wheels? I thought that was on here somewhere but I couldn’t dig it up.
 

ViperJoe

GT Owner
Mark II Lifetime
Aug 17, 2006
1,305
Washington Crossing, PA
Does anybody know the wheel dimensions and offset measurements for the stock wheels? I thought that was on here somewhere but I couldn’t dig it up.
Optional BBS light weight forged wheels are:

Front:
5-lug, 4.5" bolt circle
6.90" backspacing
50 mm offset
18" dia x 9" wide
tire 235/45ZR-18

Rear:
5-lug, 4.5" bolt circle
7.295" backspacing
40 mm offset
19" dia x 11.5" wide
tire 315/40ZR19
 

ChipBeck

GT Owner
Staff member
Mark IV Lifetime
Le Mans 2010 Supporter
Feb 13, 2006
5,608
Scottsdale, Arizona
Gentlemen,

Could somebody please give me a good understanding of exactly what "offset" and "backspacing" means as regards wheels?

Chip
 

RALPHIE

GT Owner
Mar 1, 2007
7,279
Gentlemen,

Could somebody please give me a good understanding of exactly what "offset" and "backspacing" means as regards wheels?

Chip
Offset is a measurement in millimeters from the backside of the mounting plate to the center line of the wheel. A positive number puts the mounting plate further away from the backside of the rim. A negative measurement moves it closer to the backside. Since offset is based on the center line, the width does factor in. That is to say an 8-inch wide +45mm offset and 7-inch wide +45mm offset results in a 1/2" difference in wheel positioning. The 8-inch wide will be further into the wheel well. To gain a better understanding of the offset of a wheel, read our tech article on this topic.

Backspace measures the distance from the mounting plate to the back edge of the wheel. The higher the backspace the further into the fender well it will sit.

Offset:

http://blog.tirerack.com/blog/tire-rack-team-blog/what-is-rim-offset

Offset & backspacing:

http://blog.tirerack.com/blog/hunters-ramblings/what-is-wheel-offset-and-backspace
 
Last edited:

Fubar

Totally ****** Up
Mark II Lifetime
Le Mans 2010 Supporter
Aug 2, 2006
3,979
Dallas, TX
Tremendously helpful gentlemen, thank you for the quick response!
 

Fubar

Totally ****** Up
Mark II Lifetime
Le Mans 2010 Supporter
Aug 2, 2006
3,979
Dallas, TX
Funny, I just went to add it too that tire thread and it was already there. I guess that’s where I saw before.

Thanks again!
 

2112

Blue/white 06'
Mark II Lifetime
Backspacing is so straightforward, I wish that were the predominant method of relating this issue.