In a message dated 98-06-09 14:02:55 EDT, carl_hansen@ieee.org writes:

<<
 Well, sorta, but not quite.  Let's take Michael's example of a van on
 jacks, and extend it a bit.  Imagine the van is a NON-Syncro, attach
 rubberbands, big ones, so that the rear wheels drive the front tires, and
 the tires front and back are the same size.  You will again get a
 speedometer reading, and no matter what size the wheels are (as long as
 front and back are the same), at 4000 RPM, you will get the same reading.

 So what did that prove, well, nothing actually, IN EITHER CASE.

 The actual effect of larger or smaller tires CAN ONLY be tested on the
 road.  And as Gary noted, bigger tires, means 70 mph comes up at a slower
 RPM, and with smaller tires, 70 mph comes up at a higher RPM.  It doesn't
 matter is you have a 1, 2, 3, or 4 wheel drive vehicle, it doesn't matter
 if you attach to a driven wheel, or an undriven wheel, the same is true.

 Now if you are a rally diver, you might care about undriven vs. driven
 because of wheel spin.  I can remember a REAL deap and muddy flat section
 that I knew was no longer than 1/2 mile long, but Tom and I had an
 indicated 1.2 mile on the odometer.  Lots of wheel spin, and a little fear
 that we wouldn't get to the other end and would have to have some farmer
 pull us out.

 Ch
 '89 SyncroBeast
 Prior Lake, MinneSnowta
 well, ok, it's summer
 Land of Sky Blue Waters

  >>
Hi Ch. Well now that I thought about it, you are right.  Whether or not the
speedo drive is coming from the front diff or the left front wheel the speedo
will always read    the same. I dont know why I thought it would make a
difference. I wasn't feeling very well last night. I guess if someone with a
REAR wheel drive vanagon wants to make the RPM lower without having to
recalibrate the speedo, they will have to put 28" diameter tires in the rear
only. RPM at 4000 RPM would equal 78 MPH, (3600 RPM = 70 MPH) and the speedo
will show that speed, since nothing was done at front , right.
 Michael Modl. 87 syncro