I have 195/14R tires, which are slightly larger than stock.  I checked
an on-line computer for odometer error and got a trivial difference.
Therefore, I use the trip odometer and gallons added at fill up to
calculate gas mileage.  Stock tires differ for vanagons -- and I assume
that for factory (or dealer) installed 205 tires, the correction would
have been made in the odometer by VW.

Dave Mc

On Wed, Oct 21, 2009 at 10:48 AM, Loren Busch wrote:

> RE: Calculating gas mileage
> A question for all those reporting gas mileage.  How are you
> calculating
> your numbers? Are you using the odometer/speedometer on the dash? or
> are you
> using the trip meter on a GPS?  If using the odometer, have you
> calculated
> the error in your speedo and odo and figured that in?  Are you running
> stock
> wheels and tires and if not have you figured the error induced with
> non
> stock tires?
> I ask because two discussions that get going on the list seem to
> ignore each
> other: speedometer error from different tires and gas mileage.  No one
> ever
> says that the mileage being reported is corrected for tire size/speedo
> errors.