NP> The matter would be firther obscured by the fact that the
NP> speedo is driven from the rear of the gearbox and the flat tyre
NP> is on the other side of the differential (sp?)

NP> Isn't that what a differential does ???

 I don't know how a differential works. If you jack a wheel up, does
the driveshaft read the speed of that wheel, or an average? I dunno.

NP> It would tend to hide the real difference in speed (rpm)
NP> between the inflated tyre and the partially deflated one.

 Yes, it would... but please don't make it more complicated than it
is.

 The original statement I made was that speedo reading would vary
with tyre pressure... not just a flat tyre. Roy's assertion is that
speedo hardly varies because the tyre circumference hardly varies. 

NP> The fact that I had 3/4 of a ton of wood in the back and
NP> another 1.5 tons on the trailer didn't really help. :-)

 This is another point. If you load the back and the car settles,
the speedo reading depends on the axle height. According to Roy it
doesn't vary because the circumference of the tyre hardly changes.
And pigs fly.

NP> Roy experimented and only found a small difference on the
NP> speedo. What he forgot was the DIFF is in between. !!!!

 I doubt very much that he could measure 1.7% accurately. It's silly.
To me, a single reading of 1.7% means bugger-all. It would have to be
10% before I'd even write it down.

NP> The speedo only displays the speed relative to the fastest
NP> turning wheel doesn't it??

 I dunno... but if it does, that would be the flat tyre.

Regards,
Bob


--- BQWK Alpha 0.5