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I went to a bike shop for new tires. I did not know which tires fit on my bike, so I just showed them my bike.

When I took a look at the new tires, there was a label at the side, which says:

40-622 (700x38C-28x1 5/8 x 1 1/2)

What do all these numbers mean? I am asking for two reasons:

  • I would like to find the right tires for my bike in the future myself
  • When buying another bike, I would like to buy one where I can use this tires as well
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    Note that a "700" tire is a standard European "road" tire. If you go into a bike store and ask for a "seven hundred, thirtyeight" the sales clerk (if not a total dunce) will know exactly what you mean. If you ask for a "forty, six twentytwo" they might have to check the labels.
    – Daniel R Hicks
    Commented Apr 9, 2013 at 11:35
  • Also note that if your bike came with tires of that width, you can generally go about 3mm wider or narrower (vs the "40" or "38" number) without problems (though if you go too much wider the tires may rub).
    – Daniel R Hicks
    Commented Apr 9, 2013 at 11:39
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    Related questions: bicycles.stackexchange.com/questions/10543/… bicycles.stackexchange.com/questions/9238/…
    – amcnabb
    Commented Apr 9, 2013 at 19:21
  • "So, if I look for 40-622 tire size, they will fit on my bike?" Answer: this question cannot be abswered because we don't know what tire does your bike use.
    – Dasht
    Commented Jul 5, 2017 at 3:47

1 Answer 1

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The 40 is the inflated width in mm and the 622 is the internal diameter in mm. It's the international standard ISO-5775 for tire sizes. In brackets are the French size (700mm outer diameter x 38mm width) and the Inch size (28 outer diameter x 1 5/8 height x 1 1/2 width)

Wikipedia has a very detailed explanation of tire sizes and designations, I confirmed my answer on this page.

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  • So, if I look for 40-622 tire size, they will fit on my bike? Also, if I buy a bike that has 40-622 tires on it, I will be able to use my current tires on it? Do I have to take care on the other numbers, then? That are the reasons why I am asking.
    – Uooo
    Commented Apr 9, 2013 at 9:16
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    All 40-622 tires are a standard size, if that is what your bike has on it now they'll fit. Yes, a bike with 40-622 tires will take other 40-622 tires. No, they're essentially saying the same thing for countries who don't apply to the whole ISO standard thing. Essentially one is metric, one is empirical and the other is French.
    – DWGKNZ
    Commented Apr 9, 2013 at 9:25
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    Stick with the ISO standard whenever you can, it’s the only one which makes sense.
    – Michael
    Commented Jun 28, 2015 at 7:10
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    @altomnr -- I think you're wrong. There were A, B, and D designations, in addition to C. The letter is just a part of the sizing. And, technically, the modern tire is "wired-on", not a "clincher" (though the distinction has been lost in the mists of time).
    – Daniel R Hicks
    Commented Jun 26, 2016 at 14:43
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    Why does the French system tend to specify a width that is 2mm smaller than the ISO system? That is, why is 40-622 equivalent to 700x38? Are they measured in different places?
    – Will Vousden
    Commented Jul 5, 2017 at 12:27

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