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Went to switch back to the summer wheels on the car last night and found a thorn in the sidewall just above the G of Goodyear.
The sort of thing that if it was the bike, you'd pull it out, spin the tyre and carry on, letting the sealant do its thing.
I know the tyre is borked (and less than 1000 miles old) but in desperation, I'm hoping someone will tell me I'm wrong.
Was the tyre flat? Pretty unlikely that a thorn would go through the sidewall of a car tyre...
Nope, tyre was fine. It's sat since December with the thorn in and not deflated.
I agree, you'd not expect the thorn to go through which is why I had no qualms about removing it. The thing was only 5 or 6mm long and pulled out easily with fingers.
I had a repair done on the sidewall of a tyre with literally 100 miles on it about 6 years ago. Not a normal patch but tyre place sent it away to be repaired and re vulcanised.
There are two types of tyre repair called major and minor. Minor repairs are to the centre 75% of the tread and are done anywhere (Kwik fit etc) a major repair is to the outer 25% and the sidewall. This is a bit more specialist but you should have a tyre place that'll do it. Google major tyre repair.
If it didn’t go down when you pulled it out, then why does it need a repair? I think there is some kind of guidance that if any damage is less than 10mm, and no bulging then it should be fine...
Has it left a visible hole? I'm thinking that thorns like that probably stick into car tyres frequently, and fall out again without anyone knowing they were there. If the tyre is holding air and doesn't have visible damage there's nothing to repair. But if it does need repair, it's dead - as I understand it, repairs to the sidewall are not permitted by UK law.
pics
There is a visible hole, but I've got good eyes. The reason I think it needs a repair us due to the air pissing out if it when I removed the thorn.
That would have been a useful bit of information to have included in the original post.
I doubt a thorn would have affected the tyres structural integrity, so a patch inside might be possible. You could even try putting some latex type sealant in there and letting it seal the hole?
As above, it can probably be repaired, but you may need to check with the local tyre shop that they do this type of repair. I have had this twice and one was repairable, but (due to the position of the 'damage') the second was was not so there are caveats.
put the thorn back in?
As long as it hasn't been driven on when flat (or left flat on the car for an extended duration) then a repair should be fine
How big is hole? Normally just a thorn 'prick' or similar would lead to a very slow deflation.
The tyre thickness & elasticity of the rubber itself usually seals to some extent. If you restore inner liner integrity then I would expect no further issue
If there is no fundamental damage, then a flat patch should be fine.
I would imagine to avoid a major tyre chain because I fear they won't be able to listen to your situation & will likely have standard rules of not to repair sidewall
(IAA tyre engineer)
Try this stuff - https://www.puncturesafe.com/
Not entirely sure if it will work for sidewall holes as their illustrations show punctures in the tread, but then again I can't see why it won't.
It's basically same concept as bike tyre sealant, just with a formula for car tyres, environmentally friendly and mostly permanent and doesn't write off the tyre (unlike the nasty emergency repair kit stuff supplied with cars with no spare wheel).
Used it to seal a screw stuck in the tread, all fine. Though it's aimed at putting in before punctures occur to work like bike sealant, but can be used for repairs to small holes.
put the thorn back in?
Exactly what I was thinking! Maybe with a wee dod of superglue on it.
Wheel off, a small amount of Slime in, inflate tyre and lay it over so the Slime seals the hole.
It’s worked twice so far on sidewall punctures, and passed an MOT soon after. Costs little in money and time, and also works on corroded alloy leaks.
Sounds better than my tyre yesterday.. goodyear eagle f1, 300 miles on it. Literally exploded as I drove along the road, massive slash in the sidewall. No idea what happened but I'm not a happy chap.
unlike the nasty emergency repair kit stuff supplied with cars with no spare wheel).
The garages have certainly brainwashed you with that one.
It'll be repairable, without a doubt. But getting anyone to actually do it isn't always so easy because a) people worry about liability and b) most people with the kit to dismount the tyre and fit a plug, want to sell you a tyre.
I *think* the industry position is that sidewall punctures are not repairable, so unlikely that you'll find anyone willing to do it.
Is it worth the potential downside?
The sidewall of the tyre is the main structural part and under most stress so will take some force for something to puncture through. The surface rubber is not structural so if the thorn has just penetrated that then you're probably OK. But if you've lost air, you've punctured the side wall and along the way most likely done some structural damage so proper repair and replacement is needed.
Wheel off, a small amount of Slime in, inflate tyre and lay it over so the Slime seals the hole.
It’s worked twice so far on sidewall punctures
No..you've probably been lucky...you can be lucky any number of times but it only takes one time to be unlucky. Your Heath Robinson repair has apparently succeeded due to luck rather than your skill at tyre repair. And it didn't PASS and MOT...your MOT inspector didn't notice it and would have (should have) failed it if he did.
cromolyolly
Member
Is it worth the potential downside?
The potential downside is that you get the exact same puncture you had before back. Well, except that it's very nearly impossible for a mushroom plug to fail just by their nature.
The potential downside is that you get the exact same puncture you had before back.
If it was in the tread, I'd agree. However, this is the sidewall, which is the main structural component of the Tyre. The downside of a failed sidewall repair is potentially catastrophic failure of the Tyre, loss of control at motorway speeds with high risk to the occupants and other road users. That's the downside that isn't worth trying to repair.
Most manufacturers downgrade the speed rating of repaired tyres. A proper repair, in the tread, involves unmounting the tyre to check for damage and confirm correct plugging.
As I said, I am fairly sure that manufacturers Tyre shops don't support repairing of the sidewalls, because of the rather dangerous downsides.
cromolyolly
Member
The downside of a failed sidewall repair is potentially catastrophic failure of the Tyre, loss of control at motorway speeds with high risk to the occupants and other road users.
Nope. Regardless you're still talking about a small hole in a very strong tyre. There's no route for that hole to suddenly become a massive failure- it's not under much stress, it's not a substantial structural weakness. I understand why people are paranoid about it but that's what it is, paranoia.
Not that the repair would fail in any case- mushroom plugs are as reliable as the tyre itself.
There’s no route for that hole to suddenly become a massive failure- it’s not under much stress, it’s not a substantial structural weakness.
That isn't just untrue it is dangerously untrue. Any weakness in the sidewall of a Tyre has the potential to become a very big weakness, very quickly. The sidewall is the most stressed part of the Tyre. Try tearing a piece of fabric, then make a tiny Nick in the edge and try again.
I believe you cannot use mushroom plugs in a sidewall as the flex and movement is too great, as is the stress.
It was a tiny thorn hole, the size of a needle. £24 for the repair. Tricky to find someone who does major repairs but it's done.
I posted above that I believed repairs to the sidewall are not permitted by UK law. I've attempted to find a law that says that, and haven't found an actual law, but I have found that it's stated in British Standard BS AU 159. British Standards aren't in themselves law, and only have legal force if there's a law that says they must be applied. The British Tyre Manufacturers Association say they don't condone any repair that doesn't meet the BS. If I found a tyre repairer who would do a non-BS repair, I would consider them dodgy and not trustworthy unless they had very specific expertise that amounted to re-manufacturing the tyre.
cromolyolly
Member
Try tearing a piece of fabric, then make a tiny Nick in the edge and try again.
It's not in the edge.
The trouble is that your theory is sound; it creates a weaker spot, yes. But it doesn't create a dangerously weaker spot. If tyres became unsafe because of damage like this then it'd be a constant, massive problem because minor sidewall damage is so commonplace. It's just, normally you don't even know it's happened because it remains airtight.
Maybe in the old days it was a realistic concern but for a long time now tyres have had excellent damage resistance and margin. BS 159 dates back more than 30 years. (in fact it's so old I can't even find out when it was first commissioned; but the advice on repairs is fundamentally unchanged for at least that long)
I'm not sure you know how mushroom plugs work either- movement is no problem for them and they're under effectively no stress as the air pressure fixes them in place.
It’s not in the edge.
Fair enough. Take fabric and pull on it in all directions, as hard as you can. Now cut a small slit right in the middle and do the same thing. You'll find it is considerable less able to resist the force you apply. The reason this is relevant is because the only thing in the sidewall of the tire to give it structure are the cords. Lots of them, each one designed to support around 40 lbs. Nick one, it fails increasing the forces on its neighbours by 50% and so on and so on.
Sidewall damage that doesn't affect the structure (scrapes etc) are common. Punctures/cuts etc aren't actually all that common, tread puncture are far more common.
The US version of the BS hasn't 'allowed' sidewall repairs of any kind for years, no tire places will do it and no manufacturer supports it. In the UK afaik no repair outside the centre 70% of the tread is 'minor'. Any damage outside that is 'major' and requires a hot patch of the liner over quite a large area relative to the damage. That should tell you how seriously they people who work on these things take sidewall damage.
I do know how mushroom plugs work. I also know that these days the 'correct' way to repair any penetration is by patching the liner from the inside to prevent air leakage, and plugging on the outside, more to prevent water ingress getting to the steel belts than anything else. As I said plugs are not sufficient for sidewall repairs because of the way the sidewall moves and flexes. It will not hold air for very long and will not reinforce the structure.