Tigers,
If you know geometry, you do not need to read this message.
If you are unsure, this will help you accurately determine a tires
"rolling circumference and diameter, which differ from an unloaded tire.
Please don't "calculate" the tire OD by manufacturer's sales numbers.
This is like "advertised horsepower"
1. Mark the tire side wall with a chalk vertical stripe down to the
road contact point.
2. On flat surface, with somebody in the car to steer and brake for
safety, push the car until the chalk mark meets the road. Mark
the road at this spot. Depending on how many buddies you have,
push the car forward 5 to 10 wheel revolutions, as counted by the
chalk mark, and mark the road again.
3. Measure the distance between the first chalk mark and the last,
and divide by the number of revolutions used.
4. Keeping everything in "inches" makes things simpler.
5. You now have the "rolling circumference" of the tire, which
actually changes with higher speed due to centripetal force, but
ignored for this level of accuracy.
6. Divide this number by "pi" (3.14159)
7. This is the "Circumference" of the tire.
8. Circumference = "pi" times the Diameter, therefore the Diameter is
the the "Circumference" divided by "pi".
9. Divide the measured "rolling circumference" by 3.1419 (or round
for less accuracy, to 3.14. Ignore unnamed Southern State's
legislative act defining "pi" as "3" because it is easier. Don't
use any of their bridges or hotels, either. (TRUE)
This is a lot easier than it sounds, and is spelled out, step by step,
for those unfamiliar with geometry. Those who are familiar, you really
didn't need all the words, as stated.
Thanks to Bob Hokanson for his great calculator for even more complex
calculations:
http://www.tigersunited.com/techtips/HokansonGearSpeedXL/pt-HokansonGearSpeedXL.asp
Steve
------------------------------------------------------------------------
Bob Hokanson wrote:
>Are you sure the tires are actually 22.64" diameter? My experience has been
>quite a variation between manufacturers.
>
>Bob H
>B9470168
>
>----- Original Message -----
>From: "Dave Binkley" <dbinkley@cox.net>
>To: <tigers@Autox.Team.Net>
>Sent: Tuesday, December 14, 2004 6:02 PM
>Subject: Top Secret Top Loader?
>
>
>
>
>>175R70-13 tires which calculate to a 22.64" diameter.
>>
>>
--
-----
Steve Laifman
Editor
http://www.TigersUnited.com
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