[Vwdiesel] Speedometer question

Chris Geiser geiserfam at sprintpcs.com
Fri Aug 3 00:01:36 EDT 2007

I run 205/60/15's (Michelin Agilis) on my vanagon and the speedo is pretty
accurate.  Even though they are 15's, I want to say that those are pretty
close to the original tire circumference when I checked it out.  As they
have worn (probably close to 75,000 miles on them), the speedo is a little
fast (reads faster than the van is actually going).


-----Original Message-----
From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com] On
Behalf Of dieseltdi at verizon.net
Sent: Thursday, August 02, 2007 1:21 PM
To: VW diesel mail list; diesel Vanagon Yahoo group; tdi conversions news
list news list
Subject: [Vwdiesel] Speedometer question

I am mulling over various tire sizes  for my Westy AAZ TD conversion   
to bring down the rpms in relation to the trans (1.14 3rd and .7 4th)  
and I got to thinking about the speedometer.  As I recall, the number  
on the face of the speedometer is the number of revolutions per  
mile.  Am I right on this?  The speedo in my Westy is marked with an  
820, since it gets its revs directly from the hub, on revolution of  
the tire, should equal one revolution of the cable and one revolution  
of the speedo gear, right?  Why all of this?  Well a 185/75/14 tire  
has 834 revolutions per mile but a 195/75/14 has 815 revolutions per  
mile and a 205/70/14 gets 822 revolutions per mile.  Any thoughts on  
any of this and which tire size may be best?  Of course all three  
sizes are LT or C rated tires.  Hayden

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neither Liberty nor Security."  Ben Franklin
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