Offsets

1
Continuing my research on wheels and tyres. What exactly is an offset. The wheels on my syncro are ET 37 but what do these figures mean. and can I match my ET 37 with an ET 32?. I'm getting there folks. Pulled apart the whole of the dash and placed it all back together again. Knowing my inadequacies my partner looked mortified but to her surprise I fitted it al back together perfectly. 
 
Regards

Michael


 
2
On Tue, Aug 10, 2010 at 12:30 AM, Michael Rayner <mrayner51@yahoo.com> wrote:
Continuing my research on wheels and tyres. What exactly is an offset. The wheels on my syncro are ET 37 but what do these figures mean. and can I match my ET 37 with an ET 32?. I'm getting there folks. Pulled apart the whole of the dash and placed it all back together again. Knowing my inadequacies my partner looked mortified but to her surprise I fitted it al back together perfectly.
Regards

Michael
Michael,
Offset is the distance between the mounting pad to the imaginary centerline of your wheel. For example, in your ET37 wheel, the wheel protrudes 37mm further inward than the center. ET or Einspresstief is German for 'insertion depth'.
Comparing your wheel to the stock alloy wheels on T3's: Factory alloys are usually ET30 at 6" wide. In your case, where your wheel is 6.5" wide at ET37, you take the extra 0.5" of depth and add to either side to figure how much further your rim edge will go. 0.25" (12.7mm) inward and 0.25" outward. When you add in the extra 7mm positive offset, your rim inner edge is inward 14mm further inward than a factory alloy wheel equipped Syncro. That doesn't seem much but it can make a difference when clearance becomes an issue.
IIRC, the stock T3 steel rims are ET39(?) at 5.5". Compared to that, you wheel comes in at 12.7mm (wider each side) - 2mm (smaller offset) = 10mm further inward.
I hope that made sense.
--
BenT
3
The centre of the rim is 37mm in from the mounting face of the wheel.

The standard Australian syncro 6x14" wheel is ET30
The 5.5x14 wheel is ET39



> Michael Rayner <mrayner51@yahoo.com> wrote:
>
> Continuing my research on wheels and tyres. What exactly is an offset.
> The
> wheels on my syncro are ET 37 but what do these figures mean. and can I
> match my
> ET 37 with an ET 32?. I'm getting there folks. Pulled apart the whole of
> the
> dash and placed it all back together again. Knowing my inadequacies my
> partner
> looked mortified but to her surprise I fitted it al back together
> perfectly.
> Regards
>
>
> Michael
>
>
>
>
4
Brent T

 You had me going along nicely there then you lost me at the end. How do we get from 12.7mm in and out then to 14mm with the addition of 7mm.
" 0.25" (12.7mm)  inward and 0.25" outward. When you add in the extra 7mm positive offset, your rim inner edge is inward 14mm further inward than a factory alloy wheel equipped Syncro"

Then you added

 "IIRC, the stock T3 steel rims are ET39(?) at 5.5". Compared to that, you wheel comes in at 12.7mm (wider each side) - 2mm (smaller offset) = 10mm further inward."  and I was gone. 

But Ben T and Scott Daniels  you are both champions and a great asset to have onboard our Aussie site. Just let me mull over those figures again and see if I can eke it all out.
 
Regards

Michael


From: BenT Syncro <syncro@gmail.com>
To: Syncro_T3_Australia@yahoogroups.com
Sent: Tue, 10 August, 2010 5:52:02 PM
Subject: Re: [Syncro_T3_Australia] Offsets

 



On Tue, Aug 10, 2010 at 12:30 AM, Michael Rayner <mrayner51@yahoo. com> wrote:
Continuing my research on wheels and tyres. What exactly is an offset. The wheels on my syncro are ET 37 but what do these figures mean. and can I match my ET 37 with an ET 32?. I'm getting there folks. Pulled apart the whole of the dash and placed it all back together again. Knowing my inadequacies my partner looked mortified but to her surprise I fitted it al back together perfectly. 
 
Regards

Michael
 
 
Michael,
 
Offset is the distance between the mounting pad to the imaginary centerline of your wheel. For example, in your ET37 wheel, the wheel protrudes 37mm further inward than the center. ET or Einspresstief is German for 'insertion depth'.
 
Comparing your wheel to the stock alloy wheels on T3's: Factory alloys are usually ET30 at 6" wide. In your case, where your wheel is 6.5" wide at ET37, you take the extra 0.5" of depth and add to either side to figure how much further your rim edge will go. 0.25" (12.7mm)  inward and 0.25" outward. When you add in the extra 7mm positive offset, your rim inner edge is inward 14mm further inward than a factory alloy wheel equipped Syncro. That doesn't seem much but it can make a difference when clearance becomes an issue.
 
IIRC, the stock T3 steel rims are ET39(?) at 5.5". Compared to that, you wheel comes in at 12.7mm (wider each side) - 2mm (smaller offset) = 10mm further inward.
 
I hope that made sense.
 
--
BenT

 
5
OK got that bit Phil.... but what does that all mean . What can or can't I do with that wheel. Are there limitations to what an ET can  or can't do.
Sorry to be so pedantic.
 
Regards

Michael


From: "plander@optusnet.com.au" <plander@optusnet.com.au>
To: Syncro_T3_Australia@yahoogroups.com
Sent: Tue, 10 August, 2010 5:52:37 PM
Subject: Re: [Syncro_T3_Australia] Offsets

 

The centre of the rim is 37mm in from the mounting face of the wheel.

The standard Australian syncro 6x14" wheel is ET30
The 5.5x14 wheel is ET39

> Michael Rayner <mrayner51@yahoo.com> wrote:
>
> Continuing my research on wheels and tyres. What exactly is an offset.
> The
> wheels on my syncro are ET 37 but what do these figures mean. and can I
> match my
> ET 37 with an ET 32?. I'm getting there folks. Pulled apart the whole of
> the
> dash and placed it all back together again. Knowing my inadequacies my
> partner
> looked mortified but to her surprise I fitted it al back together
> perfectly.
> Regards
>
>
> Michael
>
>
>
>


 
6

See attached illustration and ignore the US spelling.  How they curb their kerbs, I have no idea!

 

 

 

7

And this is why it is important to the steering geometry.  In nearly every design, the king pin axis and the centre of the tyre contact point coincide at the road surface.  When fitting different wheels than the original, it pays to select the offset that replicates the original design.  The green line on the right hand side of the drawing is the kingpin axis.  The orange line is the centreline of the wheel; where it meets the road is the tyre contact point.

__

8
Doesn't look like a US spelling if they spell middle as "centre".

;-)


BenT

Sent by my positive offset

On Aug 10, 2010, at 1:15 AM, "Les Harris" <leslieharris@optusnet.com.au> wrote:

See attached illustration and ignore the US spelling.  How they curb their kerbs, I have no idea!

 

 

 

spId=1709926240/msgId=10368/stime=1281428244" width="1" height="1">
<Wheel Offset.gif>
9
Message
Tyre Contact Point
 
Les,
 
What this means then is that if you are going to a taller tyre, you should reduce you ET, to make sure that the green line and orange line meet at the tyre contact point?
 
Ralph 
 

And this is why it is important to the steering geometry.  In nearly every design, the king pin axis and the centre of the tyre contact point coincide at the road surface.  When fitting different wheels than the original, it pays to select the offset that replicates the original design.  The green line on the right hand side of the drawing is the kingpin axis.  The orange line is the centreline of the wheel; where it meets the road is the tyre contact point.

__

10

Bang on!

 

From: Syncro_T3_Australia@yahoogroups.com [mailto: Syncro_T3_Australia@yahoogroups.com ] On Behalf Of Ralph Roden
Sent: 10 August 2010 21:48
To: Syncro_T3_Australia@yahoogroups.com
Subject: RE: [Syncro_T3_Australia] Offsets

 

 

Tyre Contact Point

 

Les,

 

What this means then is that if you are going to a taller tyre, you should reduce you ET, to make sure that the green line and orange line meet at the tyre contact point?

 

Ralph 

 

And this is why it is important to the steering geometry.  In nearly every design, the king pin axis and the centre of the tyre contact point coincide at the road surface.  When fitting different wheels than the original, it pays to select the offset that replicates the original design.  The green line on the right hand side of the drawing is the kingpin axis.  The orange line is the centreline of the wheel; where it meets the road is the tyre contact point.

__