gears/gearing

[greg.rocco at gmail.com (Greg Pallett)]

Part of my pre-cinty plans involve a 4k transmission with a .75 5th swap.
This has led me to paying particular attention to road speeds vs. engine
rpm.
The list has that nifty gear/speed calculator, but I see some discrepancy in
it or in my speedometer readings.
Here's the link to the picture, with the stock 4k
http://smg.photobucket.com/albums/v613/g-rocco/?action=view&current=gears.jpg
(that;s my good luck Joe Pitstop figure  - carrying a tire - in the lower
left)
accoring to the calculator, with 195/60-14's, at 3740 rpms I should
be making 73 mph, but according to my speedo I'm doing 70 or just a tick
under.
Am I splitting hairs here looking for an exact correlation?
I'm just having fun anticipating more highway fun!
Cheers,
GP

-- 
"Fatal mistakes rarely happen, but funny things often do"