Old 10-22-13, 06:04 PM
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Originally Posted by Bill Kapaun View Post
And they all pretty much use circumference DIRECTLY!
I don't know why you want to go off on a tangent? Did you just learn about PI?
2% is 2% no matter what method you use!

It's the radius (the height of the hub center from the ground) that is affected by the load on the tire (and the air pressure).

More-weight/less-pressure means a smaller radius (the hub center is closer to the ground).

It's the radius, at that one place, that causes the difference in the apparent circumference.

The radius is key to understanding why measuring the circumference of the tire isn't really a good approach and why the roll-out measurement is.

Last edited by njkayaker; 10-22-13 at 06:16 PM.
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