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Does anyone have any experience of using puncture resistant tyres when they have been cut so badly as the object pierces the tyre right through?

Being Mr. Unlucky, 2-3 months ago I managed to get a puncture on my Schwalbe Marathon Plus'.

I changed the tub initially. When the second, third puncture happened, I started looking closer. The object (what I am guessing was a piece of glass, from memory) cleanly cut straight through the "SmartGuard layer".

Image showing puncture site

Image showing puncture hole on the inside of the tyre

My guess was the object was still embedded in the tyre as it took 1-2 days after fixing punctures 2, 3, 4 for next puncture to flatten the tire completely.

I examined the site, and tried to clean it out with a pair of tweezers, narrow knife, etc.

What are my options to continue using this tyre? I have (rightly or wrongly) applied some patch adhesive to the outside of the tyre on the puncture site, to see what happens.

Image of tyre with patch adhesive applied to site of puncture

Or should I stop using it?

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  • I you can feel roughness so can you tube. Mark the tire before you pull the tube so you can match the hole in the tube to the tire.
    – paparazzo
    Jan 25, 2015 at 23:50
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    The tire needs to be booted in order to prevent further punctures through that site if you want to keep using it (for how long it will last is up for debate - it won't be as strong as a new tire). Park tool makes some boots as do others. Also, make sure there is no more debris in the tire.
    – Batman
    Jan 26, 2015 at 0:05
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    On any tire if you leave the debris in long enough it will work through. That is why it is a good idea to inspect the tire on a regular basis to get the debris before it goes through (especially on an expensive tire). You could try lightly sanding it to get it smooth. At 4 tubes you are 1/2 way to the cost of a new tire.
    – paparazzo
    Jan 26, 2015 at 1:00
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    Just search Park Tools tire boot. But it is just a temporary fix - get you home. The edges will rub the tube.
    – paparazzo
    Jan 26, 2015 at 17:24
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    Boots can last a long time on commuting though. A boot is just a piece of material you put on the inside surface of the tire and glue the hole on the outside. Not necessarily a permanent fix (which would be to replace the tire), but it may give you a decent life on the tire.
    – Batman
    Jan 26, 2015 at 18:23

5 Answers 5

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If I understand correctly, you continued to get punctures until you found the embedded object which you dug out with a knife and tweezers.

I have been in a similar situation many times and I suggest you try again. Punctures 1-4 where likely caused by the same object, which you hopefully removed this last time. Does the tire have a small weakness at that hole, yes. But, the casing on these types of tires is incredibly tough. That is why they roll like bricks. The tough casings however let you continue riding with small weaknesses without issue.

Just inspect it after inflating, and for a while afterwards, to see if the hole gets larger or the tube starts to breach (you usually need a larger hole for that to happen). I personally haven't had any problems with these small holes enlarging or new debris entering the hole. That said, there is a non-zero probability than an object could pass through the whole and cause more problems. If you know the tire contact patch size and you measure the area of the hole you could even compute that probability for bravado.

My only other advice is getting more practiced at finding and removing debris. I usually keep the tire oriented so the tire label is over the valve stem. That way when dealing with a flat I can track the tube flat back to the tire location quickly. Then I running my bare hands around the inside found tire until I find the sharp that penetrated the tube. Once you find it flexing the tire casing can often be enough to help loosen an embedded object so you can pull it out with your fingers, avoiding other tools such as pliers, tweezers, and knives.

Finally, stop riding over the sea of broken glass and all will be well!

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  • +1 for "stop riding through glass"
    – Criggie ♦
    Jun 20, 2018 at 5:45
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If the hole in the tire is large you need to install a "boot". This is some sort of heavy-weight material, installed on the inside. The purpose is to prevent the tube from bulging out through the hole in the tire and popping.

The "boot" can be many different things. Many folks swear by simply folding a US dollar bill about 3 times, then putting the folded bill in place between the tire and tube, covering the hole. Some people cut pieces of sidewall out of old tires to be used as boots. You can also use a heavy-weight tire patch. And there are purpose-made boots sold by companies such as Park Tools.

A properly booted tire should last nearly as long as an undamaged one.

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If it's a folding tyre (rather than a wire bead), you can just turn it inside out and inspect the puncture site. If something's still lodged in there, you'll be able to see it (or feel it - carefully, since it's sharp). Then, push it out from the inside.

It's worth brushing down the inside of the tyre while you have it off, in case the tip of the sharp snapped off and is still rattling around in there.

Finally, you can get a toughened variant of superglue which is ideal for glueing up cuts - search for flexy cyano glue. It doesn't repair the breaker strip to original strength, but closes the surface cut which will otherwise accumulate grit and wear more quickly.

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I suspect that in spite of cleaning, there are still some sharp leftovers in the puncture site. You can try to get them out. Since you have glued the puncture spot, that might turn out to be quite difficult if not impossible. Personally, I would call it quits after 5-6 punctures, and get myself a new tire.

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If the hole is small you can continue to use the tire. Leaving the debris in caused your other flats. This can happen on the best tire.

Sticking a patch was a good move, but generally you should stick them to the inside of the tire so that it's between the casing and the tube. If you leave it outside it's going to rub off. This isn't mandatory, but it could help prevent other debris going in the hole and piercing your tube.

And as always, look where you roll and avoid debris as much as you can.

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