Date:         Fri, 27 Mar 1998 13:41:12 -0500
Reply-To:     Michael Sullivan <sullivan@OPENMARKET.COM>
Sender:       Vanagon Mailing List <Vanagon@vanagon.com>
From:         Michael Sullivan <sullivan@OPENMARKET.COM>
Organization: Open Market
Subject:      Re: MB/Audi rim dangers.....?
Comments: To: Vanagon@VANAGON.COM
Content-Type: text/plain; charset=us-ascii

Actually your math is a bit off. The wheel to compare is the Vanagon 6" alloy
which has 35mm offset. Plugging this number into your formula you get:

6"=152mm /2 = 76mm - 45mm = 31mm
versus
6"=152mm /2 = 76mm - 35mm = 41mm

which is a 10mm difference times two for a total 20mm shorter track -- no
longer "dick all" at all.

It get worse if you compare it to a 7" wide rim with the proper 23mm offset.
The difference between a 6" wide rim with 45mm offset and a 7" rim with 23mm
offset is about 2 1/2" less track. Unfortunately, many Vanagon drivers are
using 6" rims for their "oversized" tires when 7" would be optimal in the
first place (e.g. BFG 27x8.5 will just barely work with 6" but are much better
off with 7" rims).

NOTE: the reason you don't see people using 7" rims with 45mm offset is that
the extra width towards the INSIDE would seriously interfere with the
suspension. Also note: the above discussion is totally independant of the
diameter of the wheel -- it doesn't matter whether we are talking about 14",
15" or 16" rims -- the key thing is offset.

Cheers,
MJS



Tim Smith wrote:

> Hi,
>
> I've added the Audi rims, in 15x6" size.  They are 45mm offset, vs the 35?
> for stock vanagon.  The rims are 6" vs 5.5", a difference of 12.5mm wider.
> So if I look at where the tread centre line on the stock rims was compared
> to the 15" Audi's I get (45-35)-12.5/2 = 3.75mm. A hair over 1/8" shift,
> more technically known as dick all.
>
> Keeping the SAME offset while going to WIDE tires is a problem, tire
> centreline moves way out, bearing forces do go up, tracking/stability and
> steering effort may all change.
>
> I'm keeping my wheels on, the choice of tire types/brands in 15" is worth
> the 1/8" ;)
>
> bye, Tim
>
> PS:  I'd be most concerned about rough machining of the rim centres, clean
> that up with a file and emery cloth to get it radiused and smooth.  Sharp
> corners start fatigue cracks more easily.



--
Michael J. Sullivan
Director of Catalog Design
Open Market Inc.
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