I got an old bike an the tires are all crumbling so I need to change them. I'm new to changing tires but I know I need to look for the model that on the current tires it is "650x35B - 26x1 1/2". I looked online but I couldn't find tires with the exact same definition, so my question is are there any other types that would fit? I'm also interested into knowing what kind of air chamber should I search for that fits the same size.

Thanks in advance for the help!

  • 2
    Bike tire sizing is confusing, but even so, this confuses me. The 650B size (in French sizing) is usually referred to as 27.5" (in inch sizing). Examine your tire more closely and look for a code like "ETRTO 584" or "ISO 584" (which is an unambiguous sizing system). Report back what you see.
    – Adam Rice
    Sep 6, 2021 at 14:43
  • @AdamRice 650B and 27.5 are the same diameter. When 650B tires larger than 2" were up and coming as a mountain bike size, certain industry players (Kirk Pacenti was a major one) began pushing the 27.5" moniker based on the idea that 650B is a little too numbers-and-lettersy for the mountain biking public to deal with. Sep 6, 2021 at 15:16
  • @NathanKnutson Right. So I'd expect to see 650B/27.5" markings, not 650B/26" markings, as seems to be the case here.
    – Adam Rice
    Sep 6, 2021 at 15:58
  • @AdamRice 27.5" usually only goes on the mountain bike 584 tires. It's the same kind of relationship as 700C and 29". Sep 6, 2021 at 16:30
  • Oh, and: 26 x 1 1/2" is an old nominal name for 650B aka 584mm. It still shows up on some tires and tubes in an attemp to avoid confusion, particularly of the straightforward city/utility sort, since many of the old tires and tubes being replaced will have it on there. It's a similar hard to break cycle as how so many 700x35 tires that go to the scandi markets are behooved to say 28x1-3/8". Sep 6, 2021 at 16:34

1 Answer 1


That tire size will be written on most current relevant tires as 650Bx35. The ISO designation for the same size is 35 - 584 (it's another way of saying exactly the same thing as 650B x 35, and some tire manufacturer sites use the ISO number.) The exact width match (the 35mm part) can be fudged a little if needed depending on whether a bigger tire can fit in the frame/fork/fender. Today you can find 35mm wide 650B tires, but there are more options starting at the 37 - 584 size. Panaracer, Continental, and Schwalbe all make utilitarian tires in that size that are at home on old French city bikes etc.

For tubes, most tube manufacturers now have a size in their line that's labelled as a proper 650B tube, i.e. you can buy one that just says 650Bx35-42 or whatever on it. 650B tires take 26" (559) tubes without issue and some manufacturers (Schwalbe) still have the same tube box say both 26x1.5" and 650Bx38, for example. In other words, if what you come up with is a tube box that says 26x1.25-1.75" or the like, that will work fine.

  • Thanks for the answer! I went to a bike shop and they suggested me the model 32-630 | 27x1 1/4 . They seemed a bit confused though like they didn't really know what to give me. Do you guys think this model would fit?
    – Dantert
    Sep 7, 2021 at 11:06
  • @Dantert No, that is a different size completely (27") and will not fit. The tire size you have is niche and many shops won't just have it, but there are plenty of options you can just order. Tires to look at: Panaracer Col de La Vie, Rene Herse Loup Loup Pass, Continental Ride Tour, various Schwalbe Marathon family models. Again what you really need to figure out is whether you can run a 37 instead of a 35, because where you do have very limited options is 650B tires at 35mm or less. That may require a bike shop that knows about bikes, i.e. a different one than the one that suggested a 27. Sep 7, 2021 at 16:53
  • Thanks Nathan that helps!
    – Dantert
    Sep 15, 2021 at 11:21

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