I should point out that my '85 Westy (GPS shows 66 when speedometer
shows 65) is running Nokian Hakkapeliitta 185 x 14 tires which have the
same diameter as the original tires.

Mike

Mike Collum wrote:
> The speedometer in my 2000 Beetle reads 67 when the GPS says 63 (4 miles
> per hour difference at that speed ... on the safe side).
>
> I used the GPS in my '85 Westy, during the trip to BusFusion, and (Boy
> was I surprised) the GPS consistantly showed 66 whe the speedo said 65.
>  Just the opposite of what it "should" be.  At least now I know.
>
> There are speedometer shops that can calibrate them but I don't know
> what they charge.
>
> Mike
>
>
>
> Michael Elliott wrote:
>
>> I know this is a done-to-death subject, but I searched the archives and
>> didn't turn up what I was looking for:
>>
>> The facts, as I know them:
>>
>> According to yesterday's "speedometer check" signs posted by the side of
>> Interstate 8, my odometer is a smidge optimistic: when I had traveled 4
>> miles, the odometer read 4.1 miles. Close enough for me. 2.5% error.
>>
>> The speedometer reads pretty low. According to the "Your Speed Is"
>> automated trailers with giant speed displays parked on the streets AND
>> according to my GPS, the speedometer is WAY optimistic: when I'm going
>> 65mph the speedometer thinks I'm going 75. This is a fixed percentage:
>> as I go slower, the mph error is smaller but the percentage error is the
>> same. About 8 - 9%.
>>
>> So the odo is acceptably accurate, the speedo is not so accurate.
>> Anything a fellow can do other than just mentally correct the speedo
>> reading?
>>
>> --
>>
>> Mike "Rocket J Squirrel" Elliott
>> 71 Type 2: the Wonderbus
>> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
>> Carlsbad, CA
>> KG6RCR
>>
>