[DeTomaso] 17-inch wheel back spacing
Julian Kift
julian_kift at hotmail.com
Mon Aug 11 23:18:39 EDT 2014
The problem with that logic is the 8" and 10" Campi's were designed for a rear application and both have a 5.25" backspace (yes I am aware the 8" were available on the front of true GTS cars). Here's some alternative thoughts; 10" Campi's fill the rear wheel well on a narrow body car so you need to leave that outside edge where it is i.e. put all the additional width on the inside leading to a minimum 6.25" backspace, but that still doesn't allow for the taller 17" tires and potential fender rubbing.
I think a search will turn up that near every vendor is aligned with that thought and supplying 6.5" backspace on a 17x11 wheel. I had the PI '5 Star' wheels in 17x11 and 17x8 on my '74 and the rear BS was 6.5"
Similarly on the front, yes Campi 15x8's are used on the front so 5.25" backspacing can work, however most aftermarket 17's are supplied with 4.75" as this again helps with taller tires and inner fender rub (steering lock). This is what the PI '5 star' wheels I referred to earlier were and I ran a 245/45 tire with rolled fender lips and yes the tires rubbed on the inner fender at excessive steering lock.
Julian
> From: doug351c at gmail.com
> To: MikeLDrew at aol.com
> Date: Mon, 11 Aug 2014 18:58:38 -0700
> CC: detomaso at poca.com
> Subject: Re: [DeTomaso] 17-inch wheel back spacing
>
> Let me explain further.
>
> The 5.25" back spacing for the stock 8x15 should directly apply to the 8x17
> for the front. Wheel diameter doesn't affect where the edges of the tire
> are for a given tire width and outer tire diameter. For a stock bodied
> Pantera that has had its spacers removed, you can't go any crazier than a
> 245mm wide tire on the front and sometimes you have to drop back to 235 or
> 225 depending on the particular car.
>
> At the rear, if you put 1/2 the additional 1" wider wheel width on each side
> of the wheel, all you'll get is a wider tire section width near the rim with
> the same section width at the crown of the tread. For an 11" wheel vs the
> 10" Campy, a 5.75" back spacing achieves this because it is the stock 10"
> wide Campy's 5.25" backspace + 1/2 the additional wheel width. The tire
> center remains at the same point on the car with either the stock 8x15 Campy
> or the 8x17. What could be a safer choice that this?
>
> Doug Braun
>
> -----Original Message-----
> From: Mike Drew [mailto:MikeLDrew at aol.com]
> Sent: Monday, August 11, 2014 5:42 PM
> To: <doug351c at gmail.com>
> Cc: POCA Forum Mailing List
> Subject: Re: [DeTomaso] 17-inch wheel back spacing
>
>
> Thanks Doug. But as I said, back spacing for different size wheels isn't
> really useful. I appreciate your effort nonetheless!
>
> Mike
>
> Sent from my iPhone
>
> On Aug 11, 2014, at 17:38, "doug351c" <doug351c at gmail.com> wrote:
>
> > Mike,
> >
> > My records show the following stock Back Spacings (rim mounting face to
> > inner rim edge):
> >
> > Stock Campy, 7x15 4.25"
> > 8x15 5.25"
> > 10x15 5.25"
> >
> > I used 5.25" back spacing for both my front and rear 8x16" and 10x16"
> > Compomotive wheels.
> >
> > But for an 11" wide rim I can't tell you where to put the extra inch but
> > splitting the difference at 5.75" might be pretty close.
> >
> > Doug Braun
> >
> > -----Original Message-----
> > From: DeTomaso [mailto:detomaso-bounces at poca.com]On Behalf Of Mike Drew
> > via DeTomaso
> > Sent: Monday, August 11, 2014 5:10 PM
> > To: detomaso at poca.com
> > Subject: [DeTomaso] 17-inch wheel back spacing
> >
> >
> > Guys,
> >
> > Somebody has asked me what optimal back spacing would be for 17x8 and
> 17x11
> > wheels?
> >
> > Since back spacing varies with wheel width, the spacing of wheels with
> other
> > than these dimensions is irrelevant. If you know 17x8 and 17x11 numbers
> > please let me know.
> >
> > Thanks!
> >
> > Mike
> >
> > Sent from my iPhone
> > _______________________________________________
> >
> > Detomaso Forum Managed by POCA
> >
> > DeTomaso mailing list
> > DeTomaso at poca.com
> > http://poca.com/mailman/listinfo/detomaso_poca.com
> >
>
>
> _______________________________________________
>
> Detomaso Forum Managed by POCA
>
> DeTomaso mailing list
> DeTomaso at poca.com
> http://poca.com/mailman/listinfo/detomaso_poca.com
-------------- next part --------------
The problem with that logic is the 8" and 10" Campi's were designed for
a rear application and both have a 5.25" backspace (yes I am aware the
8" were available on the front of true GTS cars). Here's some
alternative thoughts; 10" Campi's fill the rear wheel well on a narrow
body car so you need to leave that outside edge where it is i.e. put
all the additional width on the inside leading to a minimum 6.25"
backspace, but that still doesn't allow for the taller 17" tires and
potential fender rubbing.
I think a search will turn up that near every vendor is aligned with
that thought and supplying 6.5" backspace on a 17x11 wheel. I had the
PI '5 Star' wheels in 17x11 and 17x8 on my '74 and the rear BS was 6.5"
Similarly on the front, yes Campi 15x8's are used on the front so
5.25" backspacing can work, however most aftermarket 17's are supplied
with 4.75" as this again helps with taller tires and inner fender rub
(steering lock). This is what the PI '5 star' wheels I referred to
earlier were and I ran a 245/45 tire with rolled fender lips and yes
the tires rubbed on the inner fender at excessive steering lock.
Julian
> From: doug351c at gmail.com
> To: MikeLDrew at aol.com
> Date: Mon, 11 Aug 2014 18:58:38 -0700
> CC: detomaso at poca.com
> Subject: Re: [DeTomaso] 17-inch wheel back spacing
>
> Let me explain further.
>
> The 5.25" back spacing for the stock 8x15 should directly apply to
the 8x17
> for the front. Wheel diameter doesn't affect where the edges of the
tire
> are for a given tire width and outer tire diameter. For a stock
bodied
> Pantera that has had its spacers removed, you can't go any crazier
than a
> 245mm wide tire on the front and sometimes you have to drop back to
235 or
> 225 depending on the particular car.
>
> At the rear, if you put 1/2 the additional 1" wider wheel width on
each side
> of the wheel, all you'll get is a wider tire section width near the
rim with
> the same section width at the crown of the tread. For an 11" wheel vs
the
> 10" Campy, a 5.75" back spacing achieves this because it is the stock
10"
> wide Campy's 5.25" backspace + 1/2 the additional wheel width. The
tire
> center remains at the same point on the car with either the stock
8x15 Campy
> or the 8x17. What could be a safer choice that this?
>
> Doug Braun
>
> -----Original Message-----
> From: Mike Drew [mailto:MikeLDrew at aol.com]
> Sent: Monday, August 11, 2014 5:42 PM
> To: <doug351c at gmail.com>
> Cc: POCA Forum Mailing List
> Subject: Re: [DeTomaso] 17-inch wheel back spacing
>
>
> Thanks Doug. But as I said, back spacing for different size wheels
isn't
> really useful. I appreciate your effort nonetheless!
>
> Mike
>
> Sent from my iPhone
>
> On Aug 11, 2014, at 17:38, "doug351c" <doug351c at gmail.com> wrote:
>
> > Mike,
> >
> > My records show the following stock Back Spacings (rim mounting
face to
> > inner rim edge):
> >
> > Stock Campy, 7x15 4.25"
> > 8x15 5.25"
> > 10x15 5.25"
> >
> > I used 5.25" back spacing for both my front and rear 8x16" and
10x16"
> > Compomotive wheels.
> >
> > But for an 11" wide rim I can't tell you where to put the extra
inch but
> > splitting the difference at 5.75" might be pretty close.
> >
> > Doug Braun
> >
> > -----Original Message-----
> > From: DeTomaso [mailto:detomaso-bounces at poca.com]On Behalf Of Mike
Drew
> > via DeTomaso
> > Sent: Monday, August 11, 2014 5:10 PM
> > To: detomaso at poca.com
> > Subject: [DeTomaso] 17-inch wheel back spacing
> >
> >
> > Guys,
> >
> > Somebody has asked me what optimal back spacing would be for 17x8
and
> 17x11
> > wheels?
> >
> > Since back spacing varies with wheel width, the spacing of wheels
with
> other
> > than these dimensions is irrelevant. If you know 17x8 and 17x11
numbers
> > please let me know.
> >
> > Thanks!
> >
> > Mike
> >
> > Sent from my iPhone
> > _______________________________________________
> >
> > Detomaso Forum Managed by POCA
> >
> > DeTomaso mailing list
> > DeTomaso at poca.com
> > http://poca.com/mailman/listinfo/detomaso_poca.com
> >
>
>
> _______________________________________________
>
> Detomaso Forum Managed by POCA
>
> DeTomaso mailing list
> DeTomaso at poca.com
> http://poca.com/mailman/listinfo/detomaso_poca.com
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