I use a different method to detect speedometer error.  While traveling on
some sections of the interstate I time myself at a steady speed between the
mile markers.  Later I calculate the average speed and compare that to the
indicated speed.

Later,

Chris,
'85 Westy
The Usual Disclaimers Apply

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf
Of Dick Bowie
Sent: Monday, August 20, 2001 7:08 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Speedometer calibration

Hi there
The complete exact size of my left front tire is 195/75R14C.
The small number printed on the dial of my speedometer face near the center
is 500.
Hope this helps track down the error.
Bye for now, Dick
'88 Westy
'90 Miata