Tire "Volume"

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mellowJohnny
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Joined: Thu Aug 16, 2012 12:56 am
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by mellowJohnny

I ordered a pair of 23mm Conti Grand Prix tires for my training wheels recently to replace the stock 23mm Mavic rubber they came with. Since the bike is still firmly connected to the traininer right now, I only changed the front tire. Then my eyes played tricks on me. That front Conti looked *way* bigger than the Aksium - but both are "23mm". But it wasn't just the width, it was the "volume". The Conti just looked like a ballon compared to the skinny Mavic.

So I measured:

23mm Mavic Aksium: 21.46mm wide, 21mm tall sidewall
23mm Continental Grand Prix: 23.29mm wide, 24.5mm tall sidewall

Then it got me thinking: car tires are sold with three measurements (radius, width, sidewall hight), yet bikes tires only label radius and width. Lots has been written about the benefits of wider rubber, but I gotta think the overall tire "volume" plays at least an equal part in the comfort and control.

Maybe it's just these two brands that happen to be so different - anyone else noticed drastic differences across "similar" tires?

HillRPete
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by HillRPete

mellowJohnny wrote:Then it got me thinking: car tires are sold with three measurements (radius, width, sidewall hight), yet bikes tires only label radius and width.

This is down to the construction. A car tyre's steel belt keeps its cap flat, so you can make it higher or wider. A bike tyre is much more flexible, so if the casing is bigger, both height and width will grow. (Unless maybe some really sturdy MTB tyres which also have a concept of "shoulder").

In general, aberrations of 1-2mm from the specified width are not unheard of, for road tyres. MTB ones even more.

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WMW
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by WMW

wassertreter wrote:A bike tyre is much more flexible, so if the casing is bigger, both height and width will grow.


Best way to measure a tire is to flatten it and take the bead-to-bead dimension.
formerly rruff...

bm0p700f
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by bm0p700f

Conti tyres are well know to have a high aspect ratio compared to other brands.

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