Gday Ben and Les and ALL,
Well well well, live and learn eh and thanks a lot for your
contributions. Sounds to me then it would be no simple task to actually
measure an ET while a tyre is on the rim, let alone on the vehicle.
So here I am thinking all along my Merc ET49 rims were tracking wider
and hence offering greater stability, not narrower as per your
explanation. The proof in the pudding then I suppose would be to try
measuring the outside tracking width wheel to wheel of the Merc 15" and
compare that to the Syncro 14" tracking width, as they are both 6" rims.
By your explanation then, I should find the Merc 15" overall width is
narrower.
In my case, the Merc ET49's never rub on the suspension, only on those
small black plastic splash guards on the rear of the wheel arches,
usually when on either lock. And when I bought the syncro, there were no
rubbing marks on the splash guards at all, despite the wheels having
been on for around 15 years with 3 previous owners. The rubbing only
started in the off-road driving at Batemans Bay Syncro Tour 2007. Could
that mean then this syncro has never been off-roaded? Or else, I'm way
too overloaded.
Cheers.
Ken
--- In
Syncro_T3_Australia@yahoogroups.com, "BenT Syncro" <syncro@...>
wrote:
>
> On 11/26/07, Ken unclekenz@... wrote:
> >
> >
> > Gday ALL,
> >
> > Probably not just for me, would someone please explain to us in
laymans
> > terms, from where to where on the wheel rim and/or centre that is
the ET
> > offset. So, as my original (but now spare) set of 14" syncro rims
are
> > marked ET30, I'd like to be able to physically measure it and other
> > rims.
> >
> > Ben T says up to ET45 on 15" rims still won't rub. He may well be
right.
> > I do know my Merc 6Jx15H2 ET49 wheels do rub, for some occasions on
> > uneven offroad circumstances when on a lock. Also the centres in
these
> > Merc rims are only about 3.5mm thick, whereas my 14" syncro rims are
> > around 4.5mm. These 15" Merc rims have been on since around 1992.
> > However, I still cannot see any physical damage or distortion.
> >
> > Also, as many of us are running our camper syncros at maximum and
beyond
> > Gross Weight of 2.5 ton, I suspect the body is sitting lower
relative to
> > the wheels. Hence an increased possibility of rubbing.
> >
> > Cheers.
> >
> > Ken
>
>
>
> Ken,
>
> To elaborate on Les' response to your question, the bigger the "ET"
number,
> the more the inside rim of the wheel goes inward. It is also important
to
> consider the width of the wheel. For example, if you have an ET30
wheel
> which is the same offset as stock but go to a width of say... 11
inches. The
> inside rim will still make contact with the suspension components. For
our
> purposes, I feel we should limit wheel width to 7 inches at ET30.
Anything
> wider requires adjusting the ET accordingly. As another example, I
have a
> 2wd Vanagon (T3) with 8" wide wheels. I had to correct the offset to
ET20 to
> get it to fit though it now ticks out too far outward for full fender
> coverage. Here's a nice diagram to visualize how it works. Keep mind
out
> Syncro use "positive" offset.
>
> http://kmhafer.datsun510.com/wheel_offset.jpeg
>
> Just another note: The 6 inch (152.4mm) wide Syncro wheel at ET30 will
have
> 106.2 mm of it's total width sticking INWARDS and only to 46.2mm to
the
> outside of the fenders. If my math is correct:
>
> Centerline of the wheel is 152.4mm ÷ 2 = 76.2 mm
>
> Inside rim is 76.2mm + 30mm (ET30) = 106.2mm
>
> Outside rim is 76.2 - 30mm (ET30 again) = 46.2mm
>
> I hope that didn't make it more confusing.
>
>
> BenT
>
