David,

This is interesting - I hadn't considered the odometer could be relative to
the speedo. That puts a whole new twist on things. Sounds like I need to
borrow a GPS one of these days.

On 21 Mar 2005 at 21:31, David Marshall <mailinglist@FASTFORWARD.CA> wrote:

> Shawn,
> You are 100% right.  Tires that are around 27" tall are the most accurate
> for the stock speedometer.  Usually the speedometer is a little optimistic
> about everything.  Right now on my TriStar Syncro I have 225/75R16 which are
> 29.2" in diameter.  The speedometer is out by 7% - when it reads 100, I'm
> doing 107km/h.  The odometer is out by 11% - 100km on the odometer is really
> 111km - this is verified with a GPS on three separate occasions.
>
> The former Syncro Single Cab that I had was very accurate as I put a Jetta
> speedometer into it.  These need 950 revolutions to make 1km on the
> odometer, where the Syncro needs 1000 per 1km.  This truck had the same size
> tires (6.50R16) and the speedometer and odometer were almost spot on.
>
> Makes a big difference in the fuel economy stats when you know the exact
> distance you have travelled.
>
> David Marshall
>
> Fast Forward Automotive Inc.
> 4356 Quesnel-Hixon Road
> Quesnel BC Canada  V2J 6Z3
>
> http://www.fastforward.ca    mailto:sales@fastforward.ca
> Phone: (250) 992 7775        FAX: (250) 992 1160
>
> - Vanagon Accessories and Engine Conversions
> - Vanagon, Transporter and Iltis Sales and Importation
> - European Lighting for most Volkswagen models
>
>
> Due to the large volume of email  we  receive,  PLEASE  include  previous
> emails when responding.  This will allow us to read the complete dialogue
> in one message and will result in quicker and more  accurate  responses.
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf
> Of Shawn Wright
> Sent: March 21, 2005 8:32 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Tire trivia
>
>
> An interesting bit of trivia for this tired of the usual "tire" thread:
>
> I swapped my BFG A/T KOs from my '88 to '82 Westies in preparation for
> possible snow on our trip this week. I decided to measure the loaded
> radius of each of the tires I have on the ground:
>
> Michelin XC LT4 195/7R14: 11.75" = 858 revs/mile
> Yoko Y370 195/7R14: 11.75" = 858 revs/mile
> BFG AT KO 27x8.5R14 = 12.625" = 799 revs/mile
>
> The two spares I have in 185R14 OEM size are somewhere in between the
> above, but are not on the van.
>
> Since the speedo spec says 805 revs/mile (or 500 revs/km metric), this
> means the BFGs are actually much closer to this figure that the 195/75R14
> size, contrary to popular wisdom. Interesting trivia perhaps, or maybe I've
> just made an error somewhere?
>
> In any case, this might yield me 4mph at the same revs in my '82 Diesel :-)
> ...or it could mean more time spent in 3rd :-(
>
> Road trip time! Back in a week or so... :-)Shawn Wright
> http://zuiko.sls.bc.ca/~swright
> '85 Jetta TD (retired)
> '85 Jetta D
> '88 Westy 2.1L
> '82 Diesel Westy
>

Shawn Wright
http://zuiko.sls.bc.ca/~swright
'85 Jetta TD (retired)
'85 Jetta D
'88 Westy 2.1L
'82 Diesel Westy