Date: Mon, 12 Oct 2009 18:31:23 -0600
Reply-To: Bob Stevens <mtbiker62@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Bob Stevens <mtbiker62@GMAIL.COM>
Subject: Re: Speedometer and 15/65/205 Tires/Wheels
In-Reply-To: <E0B4F1FE-782D-4AE4-8686-C020FADD6EA2@mac.com>
Content-Type: text/plain; charset=ISO-8859-1
Melissa,The OE tire size for Vanagon was about 25.4" diameter and your
current tire is very close
at around 25.5", so it isn't too likely that your tire is messing with your
top end speed error,
if there is one. These vans have speedo error anyway. The way I found out
what my exact
error was was to use a GPS. I happened to own one now but is it possible to
borrow one
from someone and take it for a ride. I'm not so sure than any tire-size
calculation can be
of much help when the basic Van speedo setting is off anyway. You've already
mentioned
the use of the highway mile markers and that would be an estimate as well,
not actual.
Tire Rack has a bunch of information about technical tire stuff here:
http://www.tirerack.com/about/techcenter.jsp
I don't have any information about that cable modification. I simply know
now that I have
a speedo error and come across so many of those roadside speed indicators in
special
speed zones, and they so consistently tell me I'm going faster than my
speedo says,
that I have pretty much memorized the speed difference at various speeds. I
usually
just use the 10MPH increments, knowing I need to adjust up 2-3 mph at 30
indicated, and 4-5 at 50
indicated, etc. until I get to 70.
Not a very technically accurate system I've developed but it has resulted in
no speeding
tickets in 10 years.
I'd suggest using this tire size speed calculator if you're curious and want
to mess with it/one:
http://www.syncro.ca/tiresize/
bob
'87 Syncro Westy
On Mon, Oct 12, 2009 at 5:40 PM, Melissa Mourkas <westywoman@mac.com> wrote:
> I have come to the conclusion that I am not driving as fast as my
> speedometer indicates as people are racing around me and my speedo
> says I am doing 70 mph (and I thought this 1.9L was just really
> peppy!). I have 15/65/205 tires/wheels. I have been unable to
> conduct a test using mile markers as they are nearly non-existent
> around here and, no, I do not own a GPS. (I like maps). My shift
> points seem about 5 mph off the marks on the speedometer as well. I
> followed a thread on the Samba regarding this disparity:
>
> http://www.thesamba.com/vw/forum/viewtopic.php?t=345224
>
> They were claiming as much as 10 mph under at 70 mph (actually
> traveling at 60 mph). Has anyone on this list experienced this and
> have you tried this ratio-adjusted speedo cable shown in that thread?
>
> The vendor for the adjusted cable is:
>
> http://www.tacomaspeedometer.com/index/index.php?
> option=com_content&task=view&id=15&Itemid=28
>
> I apologize if this has been covered ad nauseum in the past. I will
> try to come up with something more original next time. In the
> meantime, thanks to all who choose to reply.
>
>
> Melissa Mourkas
> '84 Westy Honey Bee
> Sacramento, CA
>
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