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Re: Tire diameter

Yes, the problem is easy on paper, but it leaves out many of the
variables such as: tire pressure, tire temperature, centrifugal expansion
as a function of speed, manufactured variations, tread
stiffness/deformation, vehicle weight, etc. Truth is, it's not so simple.
The way we used to get a figure for it in bike racing was to mark the
tire and do a "roll out test." The rider would ride his bike for several
revolutions, then measure the linear distance. We did this to set our
computers as bicycle racing tires are notorious for variations in
profile. This was a good way to test because most of the variables were
imbedded in the test. 

On Fri, 9 Oct 1998 16:52:57 -0400 Robert Houk - WorkGroup Server Firmware
<Robert.Houk@East.Sun.COM> writes:
>   Hi group,
>     Tire diameter is easy: 
>	  td = ((tire width*aspect ratio*2) / 2540) + wheel dia in 
>   circumference = td * pi				77.55
>   circ (in feet) = circumference / 12		 6.4625
>   wheel revolution/ mile = 5280 / circ 	       817.021 

Adam Nelson '85 4000S, Blaupunkt cassette, Starbucks go cup, '69 Beetle,
1 piece
windows, hand held fan, '91 Vanagon, KYB Gas a Just, bug screens.
Columbus, Ohio

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