Will 26 x 15/8" tyres fit a mountain bike?

simonw · 14-05-2010 03:58PM #1

Why the hell are there so many formats for tyre sizing?
The bike came with 26 x 2, and I'm currently on 26 x 1.5
I assume that these are equivalent to 26 x 1.875, which should be fine, but then I read this on that sheldon brown site

Brown's Law Of Tyre Sizing:
If two tires are marked with sizes that are mathematically equal,
but one is expressed as a decimal and the other as a fraction,
these two tires will not be interchangeable.

Single Malt · 14-05-2010 08:24PM

simonw wrote: »

Why the hell are there so many formats for tyre sizing?
The bike came with 26 x 2, and I'm currently on 26 x 1.5
I assume that these are equivalent to 26 x 1.875, which should be fine, but then I read this on that sheldon brown site

26*15/8 is not the same as 26*1.875. They have different ETRTO numbers so are different tyres. http://www.sheldonbrown.com/tyre-sizing.html#isoetrto link explains

blorg · 14-05-2010 09:02PM

Basically tyres are sold on traditional sizing measurements that date back pre-war. The key thing is that the traditional sizing is based on the _tyre_ not the rim. So a 700C road tyre fits a 622mm rim. The "700" is the "typical" diameter of the wheel in mm including the tyre, (when this was first devised) not the rim. The ISO standard for 700C is 622mm. Similarly, modern mountain bike rims are all 559mm (actually 22") - this is also the ISO standard. You can generally find this listed somewhere (probably on the tyre) although the primary marketing is on 700C/26".

http://www.sheldonbrown.com/26/index.html

simonw · 14-05-2010 09:08PM

Cheers lads

Will 26 x 15/8" tyres fit a mountain bike?

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