Rim Offset

[pickupguy]

I am trying to understand the magic of offset. If a 15X6 23 mm offset rim is replced by a 15X8 23mm offset does it stick out 2 inches further or only 1 inch

thanks
Kerry

[Zeke]

That's tough one. Let me tell you how it works and then you can tell me the answer, 'cause I can't compute it. Offset would be zero if the bolting (mating) surface of the center of the wheel was eqaul between the outside lip and the inside lip. Backset is what the 23mm usually refers to as a measurement from the back lip to the back (of the) bolting surface, or how much the wheel sticks in over the rotor. So, offset pertains to the position of the bolt surface relative to the wheel and offset pertains to the bolt surface relative to the car.

[pickupguy]

isn't a stock 911 rim 23 mm offset? Or am I wrong there also?

[andyjboy]

This might help to explain things:

[Bill Verburg]

Originally posted by andyjboy
This might help to explain things:

It sure would be considerate to note where you stole it from

wheels

You know I went to a lot of trouble to set that up, maybe I should just dump it.

[pickupguy]

so all of this magic tells me what? is it 1 inch or 2 inches?

[Bill Verburg]

Did you happen to go to the page I referenced?
wheels

[andyjboy]

Sincere apologies Bill - I didn't remember where I'd originally seen it.

[donporfi]

1 inch. Offset is measured from the wheel centerline.

[PatrickB]

Originally posted by Bill Verburg
It sure would be considerate to note where you stole it from

wheels

You know I went to a lot of trouble to set that up, maybe I should just dump it.

NOOOOOO!!!

I was just looking for this again, and I'm glad YOUR work showed up again Bill!

This diagram is by far the best for those of us technically challenged!

[PatrickB]

While I have your attention Bill...

I was able to score a set of 9x16 Welded Fuchs made by Gary Stratton...
My question is now one of fitment. Instead of the OEM Fuch backspace of 130mm, these are 120mm. If I'm reading your chart correctly, that would mean 10mm closer to the curb side? I'm hoping these will still fit my Carrera with 244/45/16 tires... Your thought's?

[Bill Verburg]

Originally posted by PatrickB
While I have your attention Bill...

I was able to score a set of 9x16 Welded Fuchs made by Gary Stratton...
My question is now one of fitment. Instead of the OEM Fuch backspace of 130mm, these are 120mm. If I'm reading your chart correctly, that would mean 10mm closer to the curb side? I'm hoping these will still fit my Carrera with 244/45/16 tires... Your thought's?

That sounds about right. It will be very close to the lip and depend very much on the tire and suspension metrics.

[PatrickB]

Originally posted by Bill Verburg
That sounds about right. It will be very close to the lip and depend very much on the tire and suspension metrics.

Thanks again Bill!

[Zeke]

Originally posted by Bill Verburg
That sounds about right. It will be very close to the lip and depend very much on the tire and suspension metrics.

Aye, you saw my wheels and the backspace is closer to 140mm with the 255/ 40's. With about 2.5 to 3 * neg camber, no problem on mine. Me thinks it''s gonna be close for you with 20mm less backspacing as low as your car is. Bill knows a lot more than I, but he ain't seen your ride.

[PatrickB]

Originally posted by milt
Aye, you saw my wheels and the backspace is closer to 140mm with the 255/ 40's. With about 2.5 to 3 * neg camber, no problem on mine. Me thinks it''s gonna be close for you with 20mm less backspacing as low as your car is. Bill knows a lot more than I, but he ain't seen your ride.

Thanks Milt... I think
You've seen my ride, and how it's really probably too low... I'm hoping if It's raised up about .5-.75" front & rear, It might work out... I'll likely be sending pictures, and asking for suggestions in the next several weeks...

[lindemans]

The off set being the same, the additional width of the rim is equally divided on both sides: 1 inch more outward and 1 inch more inward...
Therefore off-set is often changed such that the inner side of the rim remains where it is (standard figures 6J-36 / 7J-23 / 8J-10).
This makes the additional width of the rim fully sticking outward.

[boyt911sc]

While the attached diagram/table have been around for a while now, and have been used extensively in many disccusions regarding wheel fitment, etc. I noticed something that could be confirmed or verified by the experts.

I did some measurements of the backspace (backset) for the following wheels:
911 Fuch wheels (6", 7", and 8" X 16") and 951 Fuch 7" X 16"
the resulting backspaces I obtained averaged at 121 mm.

Could I safely assume that the 112 mm backspace data on the table is a 'typo'? Please advise. Just my two-cents inquiring mind. Thanks.


TD

[Bill Verburg]

Could I safely assume that the 112 mm backspace data on the table is a 'typo'? Please advise. Just my two-cents inquiring mind.

I tak no credit for anything in that diagram, it wil be removed. Use the data in the tables and other diagrams.