[DeTomaso] Wheel offset (ET)

Bjoern Flesland bflesland at gmail.com
Thu Aug 2 02:40:21 EDT 2012


Is there a difference in how backspace/offset/ET is CALCULATED in Europe and USA?
I still don't have this nailed down!
Cheers Bjoern

Sent from my iPhone


Den 2. aug. 2012 kl. 09:23 skrev "Tomas Gunnarsson" <guson at home.se>:

> I beg to differ. The only thing BS is useful for is clearance from
> suspension parts. It's hardly used at all outside the US. An 8" rim and
> a 9" rim with the same ET and the same tire mounted will make the car
> handle pretty much the same and will give you the same tire to car
> clearances (admittedly slightly different due to different sidewall
> bulge).
> 
> Tomas
> 
> <-----Ursprungligt Meddelande----->
> From: michael at michaelshortt.com [michael at michaelshortt.com]
> Sent: 1/8/2012 11:43:46 PM
> To: Julian Kift
> Cc: guson at home.se,De Tomaso List
> Subject: Re: [DeTomaso] Wheel offset (ET)
> 
> The problem is that there are too many number flying around.
> 
> The only number that matters for 90% of most applications is
> backspacing,
> how it differs from stock.
> 
> If the backspacing is a larger number, the wheel rides inboard more, if
> it
> is a small number, the wheel sticks out more.
> 
> If the wheels are wider or smaller, you just have to do the math.
> 
> let's say a car is OEM with an 8" wheel with 4" of backspacing,
> 
> you want to buy a 10" wheel with 6" of backspacing
> 
> Your wheel is 2" inches wider, and rides inboard 2" more, therefore,
> your
> exterior appearance should not look any different.
> 
> If on the other hand, you want to use a 12" wheel with 3" of backspace,
> then the wheel will stick out past the
> 
> OEM outer most point by 1" for the backspacing plus another 4" for the
> wider wheel for a total of 5",
> 
> you are now driving a skateboard or have plans to install flares.
> 
> Michael
> 
> 
> 
> On Wed, Aug 1, 2012 at 5:34 PM, Julian Kift <julian_kift at hotmail.com>
> wrote:
> 
>> In my experience backspacing depends entirely on the wheel
> manufacturer
>> you are talking to and worth clarifying with them up front. Kodiak and
> most
>> others I have dealt with here in the US use the tire bead i.e. inner
> rim lip
>> 
>> Kodiak has a worksheet on their website, which may or may not help
> you.
>> http://www.kodiakracingwheels.com/ordering.html
>> 
>> Whose wheels do you have? I think there was a very quick jump to the
>> conclusion the part #'s represent the offset, which may or may not be
> the
>> case, but some substantiation is likely warranted.
>> 
>> Julian
>> 
>>> From: guson at home.se
>>> To: michael at michaelshortt.com
>>> Date: Wed, 1 Aug 2012 12:44:30 -0700
>>> CC: detomaso at realbig.com
>>> Subject: Re: [DeTomaso] Wheel offset (ET)
>>> 
>>> When calculating ET the reference is the middle of the tire which in
>>> turn is determined by the inner edges of the rim. You can assume
> that
>>> the outside of the edge is 1/2" further out on each side of the rim
> but
>>> especially on aluminum rims this measurement can differ from side to
>>> side on the rim. My calculations were assuming that your reference
> was
>>> the same for BS and rim width. If they weren't my calculations are
> off.
>>> 
>>> Rim width is always inside the lip. Backspacing is measured outside
> the
>>> lip like Michael says.
>>> 
>>> Tomas
>>> 
>>> <-----Ursprungligt Meddelande----->
>>> From: michael at michaelshortt.com [michael at michaelshortt.com]
>>> Sent: 1/8/2012 7:51:57 PM
>>> To: Bjoern Flesland
>>> Cc: Tomas Gunnarsson,POCA Detomasolist Realbig
>>> Subject: Re: [DeTomaso] Wheel offset (ET)
>>> 
>>> I do not think they use the lip, I think they use the outside edge,
> as
>>> in the part that touches the ground when it lays flat.
>>> 
>>> Michael Shortt
>>> 
>>> On Wed, Aug 1, 2012 at 1:43 PM, Bjoern Flesland
> <bflesland at gmail.com>
>>> wrote:
>>>> But stampings does not match quite up with the calculations that
> Tomas
>>> did.
>>>> 
>>>> So I am confused!
>>>> Can it be measured in different ways?
>>>> Cheers Bjoern
>>>> 
>>>> Sent from my iPhone
>>>> 
>>>> 
>>>> Den 1. aug. 2012 kl. 20:08 skrev "michael at michaelshortt.com"
>>> <michaelsavga at gmail.com>:
>>>> 
>>>>> Yes, I think that is exactly what that means.
>>>>> 
>>>>> Michael Shortt
>>>>> 
>>>>> 
>>>>> 
>>>>> On Wed, Aug 1, 2012 at 1:06 PM, Bjoern Flesland
> <bflesland at gmail.com>
>>> wrote:
>>>>>> Thanks for helping out.
>>>>>> They are stamped the following:
>>>>>> 
>>>>>> Front
>>>>>> 28 85 8 LA3
>>>>>> 8.5JX18H2E64
>>>>>> 
>>>>>> Rear
>>>>>> 28 13 8 LA
>>>>>> 13JX18H2E39
>>>>>> 
>>>>>> Could that indicate ET of 64 and 39 mm?
>>>>>> 
>>>>>> Cheers Bjoern
>>>>>> Sent from my iPhone
>>>>>> 
>>>>>> 
>>>>>> Den 1. aug. 2012 kl. 19:36 skrev "Tomas Gunnarsson"
> <guson at home.se>:
>>>>>> 
>>>>>> If you have used the same edges as reference for all
> measurements
>>> the narrow
>>>>>> rim has ET70 and the wide rim ET51.
>>>>>> 
>>>>>> Tomas
>>>>>> 
>>>>>> <-----Ursprungligt Meddelande----->
>>>>>> From: Bjoern Flesland [bflesland at gmail.com]
>>>>>> Sent: 1/8/2012 6:22:47 PM
>>>>>> To: POCA Detomasolist Realbig
>>>>>> Subject: [DeTomaso] Wheel offset (ET)
>>>>>> 
>>>>>> I am trying to determine the offset (ET) of two wheels and need
> some
>>> advise:
>>>>>> 
>>>>>> One wheel measure 184 mm from the mounting face/flange to the
> inner
>>> rim
>>>>>> edge.
>>>>>> Wheel width is 228 mm.
>>>>>> 
>>>>>> The other measure 216 mm from the mounting face/flange to the
> inner
>>> rim
>>>>>> edge.
>>>>>> Wheel width is 330 mm.
>>>>>> 
>>>>>> Appreciate your help. Thanks!
>>>>>> Cheers Bjoern
>>>>>> 
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>>>>> 
>>>>> 
>>>>> 
>>>>> --
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> Michael L. Shortt
>>>>> Savannah, Georgia
>>>>> www.michaelshortt.com <http://www.michaelshortt.com/>
> <http://www.michaelshortt.com/>
>>>>> michael at michaelshortt.com
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>>> Michael L. Shortt
>>> Savannah, Georgia
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> <http://www.michaelshortt.com/>
>>> michael at michaelshortt.com
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> 
> 
> 
> -- 
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> 
> 
> 
> 
> 
> 
> Michael L. Shortt
> Savannah, Georgia
> www.michaelshortt.com <http://www.michaelshortt.com/> 
> michael at michaelshortt.com
> 912-232-9390
> 
> 
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