On Wed, 27 Jan 2021 10:29:44 +0000, R D S wrote:

I've a puncture on a front tyre, it's not in the legal repair area so
will need changing.

I can't decide whether to do both. that's the advice isn't it (from tyre
sellers )

What is a shame here is how many 'perfectly good' tyres end up getting
dumped when they needn't be.

1) You drive over something and it either goes straight in and stays
there (but not causing a leak as it doesn't penetrate the inner skin)
.... or stays there till you hear it and pull it out (still not causing
a leak), or comes out (still not causing a leak).

You didn't realise you drove over something but may have damage to the
structure of the tyre but because you haven't had a puncture, you
carry on until:

a) The then tyre fails, potentially hiding the damage
b) The damage is spotted and repaired or replaced
c) The damage isn't spotted and the tyre replaced when worn out.

2) You drive over something and it either goes straight in and stays
there, not causing a leak (even though it has penetrated the inner
layer, see a, b and c above), stays there but causing a slow leak,
meaning:

d) you carry on driving on it and assuming no TPS / warning, do so at
speed without noticing, cause the tyre to heat up excessively and
eventually blow out.

e) and / or you notice it's low / flat the next time you look at that
tyre or notice it when driving, in which case you:

f) Pump it up and drive on it some more
g) Replace it with the spare and get it repaired or replaced.

or stays there till you hear it and pull it out (causing a leak), then
either f or g above.

Now, the repair in the case of say a panel pin making a clean hole
though to the inside of the tyre (and it not compromising the
structure of the tyre at all) simply requires some sort of means of
stopping the air getting out. Tyres often suffer all sorts of cuts and
holes in the treaded area that are no deeper or more dangerous than
the tread itself.

The 'problem with them repairing a leak is the amount of flex and
therefore delamination risk of any air-blocking patch that may be
vulcanised / glued to the inside. If such a patch should come loose
then the risk is no different / greater than when you got that
puncture in the first place.

The flex in the tyre is greatest near the sidewall / tread area and
hence why most places won't fix a leak there, not because doing so is
in itself dangerous (as in compromising the structure of the tyre) but
simply because it's unlikely to last. The issue isn't the goal, it's
the (typical) process used.

Now what if there was a way of blocking the hole to stop the air
leaking out that couldn't become delaminated because it wasn't stuck
over the hole but was stuck in it, from the inside?

Now we know they do that with the 'mushroom' repairs but that often /
generally involves drilling the hole out by quite an amount,
potentially then doing structural damage (cutting one or more of the
cords) in the process.

If a hole did expose one of the cords / belts and it happens to be
steel, a patch on the inside can prevent air getting out but not water
getting in and potentially rusting a steel cord / belt, causing it /
them to fail later on. Again, an 'alternative' repair could fill the
entire hole with a material that cures with heat and time and prevents
both the air getting out and water getting in.

If a larger object penetrates the tyre it could do damage without
causing any air loss (even if it goes right though). All could be well
till the object is thrown out and then the tyre could suffer a rapid
deflation and then (depending on the speed , load and distance
traveled), cause a complete tyre failure.

It's my personal preference (and has been for 20+ years now) to treat
all my tyres with a semi-liquid pre-puncture gloop (that is self
balancing, non corrosive, water soluble in it's uncured state and not
anything like most similar products or the 'emergency' get-you-home
cans) that seal any puncture up to a reasonable size and not on the
sidewall, in every case so far for the remaining life of the tyre and
*before* you will have done any damage by running the tyre when
partially deflated / deflating.

Whilst it is designed to be used pre-puncture, I have used it many
times as a post puncture repair and in no instance has the tyre leaked
further or had any other issues, often saving a perfectly good tyre
because the 'system' hasn't yet caught up to the fact that such things
exist that do work and are safe.

And why would the tyre companies push such a solution versus selling
you a new tyre?

Personally, I would much rather risk the instance when such a repair
makes any situation worse, over the though of me, my family or anyone
else being put at unnecessary risk from the more likely risks when
dealing with the consequences of a puncture.

This type of solution (excuse the pun) is already available
off-the-shelf via offering like the Continental 'Contiseal' range:

https://www.continental-tyres.co.uk/...gies/contiseal

.... and we enjoy the same level of protection from a product called
'Punctureseal'.

https://www.punctureseal.com/

That's not 'and products like it with similar names', it's
specifically that and only that product (although I'm sure others may
exist).

This includes our trailers, motorcyles, cars, vans, mobility scooters
and other peoples ride on mowers, wheelbarrows and the like.

I'm not advocating it's use over a spare wheel, I'm reflecting it's
use to prevent (in most cases) having to use the spare wheel.

Cheers, T i m