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custom size tire circumference
Posted: Mon Oct 24, 2011 9:47 pm
by jrajr
I have a new mountain bike! iDash setup doesn't list the tire size but has a custom selection, my tire size is 29x 2.75, so what number do I enter into the custom screen?
Thanks.
Re: custom size tire circumference
Posted: Tue Oct 25, 2011 8:11 am
by lorduintah
I believe the answer is 29 * 25.4 * PI or approximately 2314 mm.
This should get you close - Alternative is to mark out a complete revolution of the wheel on a surface and measure that distance the tire rolled.
Tom
Re: custom size tire circumference
Posted: Tue Oct 25, 2011 9:20 am
by jrajr
Tom,
Thanks for that calculation. I was wrong on the size though, it is 29x2.1
I would re-calculate myself but am unsure of the 25.4 figure.
Thanks
Re: custom size tire circumference
Posted: Tue Oct 25, 2011 12:57 pm
by lorduintah
25.4 mm per inch. That's where the conversion comes from.
Tom
Re: custom size tire circumference
Posted: Tue Oct 25, 2011 9:18 pm
by jrajr
Thanks. I'm American, don't understand the metric system!