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I've got a Schwalbe snow and ice 700x38 (also marked 40-622) on a Mavic A319 (19 mm internal width). This, according to Sheldon should be an ideal combination (and if it wasn't, the failure modes don't match). Other tyres seat well on the rim but this one has always been problematic: when I first fitted it last winter, and the first time this winter, the bead wanted to ping out of the hook groove. Last night I topped it up (to somewhere in between the min and max recommended pressures), got about 10 km and it came off the rim. After that I just couldn't get it to seat - pumping it up hard it came straight off the rim, pumping it up soft it came off within the first 10 metres. After several attempts (over an hour in -4°C) I had to give up and call for a lift.

Other tyres on the same rim are fine (marathon plus 32, marathon mondial 35). This tyre seemed OK on the front rim for the same bike (a 17mm Alex) but doesn't fit under the mudguard (I've got a 35mm studded tyre on there).

I'd really like to refit this tyre tonight given the weather forecast, and studded tyres are only available mail order so there's no chance of getting a replacement quickly.

Is there some way to persuade it to seat and stay seated? Does the tube width make a difference - my spare was only recommended up to 35mm but it orginally failed with one recommended up to 40mm - perhaps by exerting lateral pressure into the seat immediately rather than radial first it was persuaded to seat but only just.

Update: I've tried it on the front wheel of my 29er hardtail. It won't seat there either, and in a few attempts it popped off in a different place each time. The bead feels OK, less pronounced than some of my other tyres (which are mostly Schwalbe as well) but not enough that you'd notice unless you were trying to find something.

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    Sounds like the tyre has a damaged/defective bead to me – Andy P Jan 31 at 9:57
  • I think the Schwalbe Winters are just loose. I have also a pair that is finicky to install but fortunately stays on rims once they have been inflated. Unfortunately they might be the only good brand available. – ojs Jan 31 at 10:35
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    @Criggie we don't really get "hot" here and the garage is the shady corner of the house - no other tyres have suffered or there over several summers. The change since last year is probably the normal easing when a tyre has been inflated a couple of times. 3 different rims now, and a random spot on the tyre each time, also on the rim as I aligned the logo to the valve (most times). I could use the MTB as my snow bike then I'd have disc brakes, and the cable ties would replace the studs on show - but not last long on potentially icy roads – Chris H Feb 1 at 10:41
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    @Emyr I've now tried 3 different rims, all with the same problem. All hold all other tyres fine. I have one other rim worth trying because the bead hook seems more pronounced than I've seen on anything else, but it's dedicated to the wrong bike. – Chris H Feb 26 at 11:19
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    @Criggie I've given up. It wasn't a very icy winter round here so I'll replace it before next winter. What's strange is that I got an entire winter out of it, and a few weeks of the winter just gone, until I topped it up. Something must have tipped it over the edge and I was hoping to tip it back – Chris H Apr 17 at 6:41
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You could add one or two extra layers of cloth rim tape (e.g. velox). This increases the diameter of the rim and makes it harder for the tyre to come off.

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    I'm not sure how you think it will help the tyre stay on when the rim tape doesn't touch the tyre at all, let alone near the bead that holds it on. – Chris H Apr 16 at 16:14
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    This makes no sense at all, sorry. – David Richerby Apr 16 at 17:09
  • I see your point, but not sure it would help a lot. Raising the floor of the rim's valley will make the tube sit a little further out at the same inflated pressure. A see-saw effect means it will push slightly more on the inside of the sidewall, making the bead/hook/rim interface even worse. If there were some way to make the tube shorter and narrow so it was tight to the rim, then that might have some positive pressure against the inside of the bead hook area. Something like the two-part tube/tubeless designs. But in reality its a bad tyre and a simple replacement should work a lot better. – Criggie Apr 17 at 2:51

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