Tyre Sizes (Metric vs Imperial)

Scotch Bonnet · Scooby Slapper Joined: 23 Jul 2007 Karma :

Since my rear lost an argument with a broken bottle the other day, I've been trying to get hold of a new inner tube. Most places seem to only do a 3.00 x 18, where Honda and Haynes seem to state it as 90/90 x 18.

I realise the two are supposed to be equivalent, but is there much of a difference?

At the end of the day it's just a CG so I always feel a bit silly taking such things quite so seriously, but hey, it might be relevant later on down the line.
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Hmmmm..... is it supposed to do that?
2001 CB500

spikenipple · Crazy Courier Joined: 20 Nov 2007 Karma :

The majority of innertubes are measured in inches diameter, so a 3.00" x 18" innertube will be the right one.
The tyre is marked as a 90/90 which is width/profile in relation to width.
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map · Mr Calendar Joined: 14 Jun 2004 Karma :

FWIW tyre sizes are almost all metric sizes (ok, the numbers may refer to inches but they are metric). The only manufacturer bikes I know of (and I'll wait to be corrected) that use imperial sizes are Harley Davidson and the Yamaha Virago VX535.
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Scotch Bonnet · Scooby Slapper Joined: 23 Jul 2007 Karma :

Good to hear on the inner tube measuerments Thumbs Up

but it also applies to the tyre itself too.

For some reason the site crashes explorer on my work PC, but Honda's specs for the CG on their website uses both systems - a 2.75 at the front and a 90/90 at the back,

Having a look elsewhere I see that a 3.00 and a 90/90 are definitely different, I just don't know if i should be bothered about which they use.
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Hmmmm..... is it supposed to do that?
2001 CB500

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

3.00 is 3" wide at the widest point.

90/90 is 90mm wide and has a height which makes up 90% of the width.

90mm = 3.54".

Either tyre size will fit on the rim.

In reality, the tubes are almost certainly one and the same, what with rubber being very stretchy.
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