[DeTomaso] Wheel offset (ET)

Thu Aug 2 13:21:02 EDT 2012

 I was under the impression that wheel offset was also designed to correctly transmit loads to and through the wheel bearings. Wheel bearings, I think,?are ideally loaded in the vertical plane. Offsetting the wheel from the designed load axis introduces a constant eccentric load. I remember my buddy in high school who ran chrome reversed wheels and promptly destroyed his wheel bearings. I may well be wrong on all this. Jack, what do you say?
?
Daryl Adams
Mangusta 8MA888
?
original message-----
From: michael at michaelshortt.com <michaelsavga at gmail.com>
To: Julian Kift <julian_kift at hotmail.com>
Cc: guson <guson at home.se>; De Tomaso List <detomaso at realbig.com>
Sent: Wed, Aug 1, 2012 4:54 pm
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/> 
> > >> michael at michaelshortt.com 
> > >> 912-232-9390 
> > >> 
> > >> 
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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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--  

Michael L. Shortt 
Savannah, Georgia 
www.michaelshortt.com 
michael at michaelshortt.com 
912-232-9390 

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