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I bought a bike just over a year ago and towards December I went into my local Halfords looking to replace my tyres and was told that my wheel size (he checked on the tyre that is currently fitted which says 28x1.75) is very old and they don't stock them any more. I thought this was very strange since it was bought as a 2019 version ebike but I contacted Scott, the bike maker, and was told that the size is actually 700 x 47c so I should find something in that size - they even suggested a tyre to me which was 700 x 45

My question is this, my current tyre which was on the bike when i bought it is 28x1.75 and Scott is telling me that i should put a 700x47c tyre on my bike as that was what they were made for. From my research it looks like these sizes are similar however there does seem to be a difference... Would this even work?

Also if my bike was made for 700x47c tyres, can anyone imagine why I'd be sold one brand new, just been built in the cycle shop (Cycle Republic) with different tyres?

To add a little more confusion to this (for me at least) the rims which the tyres are on say that they are 622x25c!

This has had my head spinning for days trying to figure out all the numbers. Can anyone please give me some insight?

My desire is simple, I have a set of tyres on my bike which are 28x1.75 and ideally i would like to replace them with something like a mtb tyre (as the tyres on my bike currently are) yet the problem is I can only find slick road bike tyres which is not what I want as I often go off road on my ebike. I have run the tread down on my current tyres so they almost look like road tyres as well now, so I'm urgently in need of a new set.

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    A "28 inch" tire with a decimal width is a 700c. The 1.75 inch width translates to 44.45mm, so any 700c tire between about 38 and 48 mm wide should work. sheldonbrown.com/tire-sizing.html
    – Daniel R Hicks
    Commented Feb 24, 2021 at 1:58
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    Halfords really doesn't sound like much of a bike shop. Check whatever they say before believing or trusting. Bike tyre sizing is horribly convoluted, specially when using imperial units, so stick to metric. 622 is unconfusable, whereas 27/28/29" might all be the same size, or not !
    – Criggie ♦
    Commented Feb 24, 2021 at 7:10
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    @Criggie they're not great. They're the biggest seller of cheap bikes (that grey area between BSO and entry-level, as well as some better stuff) in the UK. Their mechanics vary from half-trained to good enough to work somewhere better (but haven't got round to it). Sales staff may have no training on bikes, as they also sell car parts/accessories and camping gear, but can be helpful (or "helpful" anyway). The shops are useful though - common, often open late into the evening, and with a reasonable stock of basic components.
    – Chris H
    Commented Feb 24, 2021 at 10:33
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    ... A much better chain alternative is Evans, better staff, better stock, only do bikes, know more about them, in most cities, also with decent opening hours (in normal times). They've been bought by Sports Direct (cheap and nasty chain of sports/outdoor wear retailers who have ruined several formerly good brands and don't treat their staff very well) so they may go downhill.
    – Chris H
    Commented Feb 24, 2021 at 10:36

1 Answer 1

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There are many questions here about this topic, but: bicycle tires (mostly) all have both an official ISO designation, which is a pair of numbers "XXX-YY" where XXX is the diameter of the bead and YY is the inflated width. If you look, you'll probably be able to find something like "622-45" somewhere on your tire.

Tires all also have at least one nominal or colloquial name, and usually more than one, and there are many instances where one of those nominal names looks similar or identical to a different size's nominal name. There is some geography and chronology at play with the whole thing.

622 is the bead diameter for 700C, 29", and the more common of the two 28" sizes. Some countries are still hooked on the 28" naming convention for what the rest of us know as either big 700C tires or in some cases little 29" ones. The other 28" size is a different bead diameter (635) altogether, and is regarded as fairly common in some parts of the world (Netherlands) and totally weirdo in many others (North America). Tires are not usually made in market/region-specific versions, so ones that might wind up sold in northern Europe and thereabouts often have all the pertinent size labels on them, the stereotypical examples being trekking, touring, and urban models from Schwalbe and Continental. It is confusing and that's why your startled shop person was confused.

The 622x25 on your rim is telling you its internal width. Internal width is the most important determinant of what your width options are that will fit on your tire.

There are many tires now made in the 700x40s "monster cross" category that should work well for you. Your bike may or may not be able to take something larger, like a 29x1.95 or 622-50 or whatever the heck, depending on its clearances. Your wheels can take them. It is wise to stick with ones that are intended for e-bikes; while not mandatory, the distinction is meaningful because those tires are overbuilt to take the constant high torque of ebikes. There are sufficiently burly tires that don't necessarily call themselves out as ebike tires that would also be fine, but there are some that would be too light and supple for the application too.

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