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After having ridden a few hundred kilometers on my MTB, I realized that I have mounted tires marked as Mount only on hooked rims... and the rims are hookless. Common sense tells me that the tires may blow off, or at least the vendor does not guarantee otherwise.

  • Is there any other concern besides possibly higher probability of tire going off the rim?

  • What can be the technical difference which makes a tire designed for "hooked rims only"?

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    Which tires are these and when did you get them?
    – Paul H
    Commented Oct 28, 2023 at 18:21

3 Answers 3

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There is a muddle of history and context here.

For decades, before the rise of hookless tubeless-compatible (often carbon) rims, many tire sidewalls of all sizes and genres said "hooked rim only" or some variation thereof, meaning don't put them on the other kind of hookless rim. This includes many tires with beads of the traditional clincher, non-tubeless style, and also some tubeless tires, which may or may not have had that warning built into the mold before hookless tubeless became popular.

The other kind in question is usually associated with older or cheaper rims, plus some traditional designs that are still common in some parts of the world. This is mostly a cost-saving feature for low-performance, low-pressure applications. (There is all sorts of other history here but it's a digression).

If it's a contemporary tubeless-compatible MTB tire and it says hooked only, that is an explicit recommendation against what you're doing, i.e. it wasn't designed and tested for hookless, or it was tested and failed. Or, it could be low-hanging-fruit avoidance of liability exposure on the manufacturer's part. You could consider second-guessing the manufacturer here, possibly making a judgement based on how strong the bead lock is when you deflate it and try to remove it by hand. Personally I would heed the warning in this case and just not do it.

There is a permutation to the above where the tire is tubeless-compatible, possibly an older one, but is labeled in a way that's oblivious to hookless tubeless rims and could be fine on them, i.e. it predates them, and the intention was only to keep it off of old cruiser rims etc. Barring further clarification from the manufacturer I would take the cautious approach there and still not do it, because you can't reliably discern anything further with what you have.

If it's any kind of non-tubeless-compatible tire, it doesn't belong on a hookless tubeless-compatible rim in any circumstance. Your teeth are worth more than that. Tubeless hookless rims rely on the tubeless bead lock for security. You might find the bead lock is providing some retention anyway, but I wouldn't risk it.

Note whether the tire is running tubeless or tubed doesn't matter in any of this.

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    +1 for recommending the cautious option, but with properly backing up why instead of just preaching it.
    – ojdo
    Commented Oct 29, 2023 at 14:34
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I am not familiar with MTBs, but I had thought that they fully transitioned to hookless rims a while ago. Thus, it seems a bit odd to get a non-hookless tire.

I would not mount it on a hookless rim. Hookless rim compatibility requires a number of tire bead specifications. I don’t know what these are, but probably the bead shape is part of it. If this were a road bike, I’d say that that tire is going to blow right off the rim, and at worst it will blow off in a corner or a descent.

MTBs are a much lower pressure application, and MTBs and cyclocross used to run unofficial tubeless setups with non-tubeless tires and not-necessarily-tubeless rims. You could take a chance on this. I would not.

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  • On gravel I have used such a non-official tubeless setup involving a TLR tyre but non-TLR rim for years, it never failed, but that is obviously on a hooked rim. I would be afraid of a hookless rim and non-hookles tyre. Commented Oct 29, 2023 at 8:14
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I have a tire for hooked rims that I run tubeless on a hooked rim, but the tire bead is damaged (long story how). Half of the rubber that normally sticks out to the side and engages the hooked part of the rim is missing on one side in a section about 7.5 spokes long (700c diameter). Despite having good tread and all punctures patched from the inside, the tire was unusable. It can't hold even 50 psi without blowing off the rim, and it's rated for a max of 90 psi!

I was about to throw it away when I realized that MTB ghetto tubeless is hookless, so there should be a way to set up my gravel tire tubeless without functional bead hooks all the way around. I'm not a mountain biker and I've never played with ghetto tubeless, but from what I remembered reading ghetto tubeless basically involves adding 2-3 layers of gorilla tape (0.432 mm thick per layer) to increase the diameter of the rim's beads. If you do the math you'll see that tiny increase in diameter corresponds to a substantial increase in circumference.

Once the rim's beads are thickened up enough it will be impossible to install the tire without an air compressor and maybe wetting the bead too. But once it's on there, having the bead that tight means it's not coming off. I moved the tire to the back, installed it with extra tape and it's holding 60 psi no problem. I ride with 60 psi or less so problem solved.

(I use a $45 compressor from Harbor Freight and a $4 blow gun from Aliexpress with the hose and head from an old bike pump hose-clamped onto the tip.)

You can also add a tubeless foam insert. That can make seating the bead far easier by decreasing the volume of air. You might not need a compressor anymore. It also seems to prevent the tire from unseating at any PSI. I think the Vittoria Air-Liners are a good example. They have versions for gravel, MTB, CX, etc.

I conducted tests on three different types of foam lately (not bike products, this is DIY crap), and not once in my testing have I seen a tire with foam in it unseat, even while riding (carefully) on it at 0 psi. And I don't just mean the tire stayed on the wheel, the beads of the tire actually stayed on the beads of the rim, regardless of which direction the tire's sidewalls were pointing at the end of the test! I rode 1/4 mile with 0 psi on all three and took the winner on a destructive 2 mile run-flat test.

That was a normal tubeless setup using the tire with the damaged bead and without any extra tape. I do suspect that I could pull a tire off the rim if I cornered really hard at 0 psi, but I haven't actually tried. YMMV with all of this.

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