Puncture Protection In A Tyre
- Thread starter Wester
- Start date
Page may contain affiliate links. Please see terms for details.
Yellow Saddle
Guru
- Location
- Loch side.
Puncture protection is not something definite, like a car with a diesel or petrol engine. It is subjective, no matter what they say on the sidewall.
Resistance to punctures is directly related to two properties of the tyre: toughness and thickness.
The latter is easy to imagine. A very thick tyre will be too thick for a short thorn to go through or, more practically, a thicker tyre will be thicker than many small shards of glass.
The second property is toughness. This is a bit more vague. Typically toughness is added to a tyre by way of a vinyl layer. Unfortunately vinyl has a very high hysteresis and robs energy and deadens the ride significantly. The thicker the vinyl, the worse the ride but better the puncture protection.
Puncture protection cannot be added by way of fibrous material like Kevlar (Aramid) or anything that has to be woven to create a mat or strip.
So, to just look at a tyre, you can't say but you can perhaps take a feel. Thicker (on the contact area) is better (for puncture protection but worse for riding and handling) and heavier likewise, better for protection but worse in every other aspect. Vinyl is much denser than rubber and thus noticeably heavy. Increased thread count is NEVER an indication of better puncture protection.
Resistance to punctures is directly related to two properties of the tyre: toughness and thickness.
The latter is easy to imagine. A very thick tyre will be too thick for a short thorn to go through or, more practically, a thicker tyre will be thicker than many small shards of glass.
The second property is toughness. This is a bit more vague. Typically toughness is added to a tyre by way of a vinyl layer. Unfortunately vinyl has a very high hysteresis and robs energy and deadens the ride significantly. The thicker the vinyl, the worse the ride but better the puncture protection.
Puncture protection cannot be added by way of fibrous material like Kevlar (Aramid) or anything that has to be woven to create a mat or strip.
So, to just look at a tyre, you can't say but you can perhaps take a feel. Thicker (on the contact area) is better (for puncture protection but worse for riding and handling) and heavier likewise, better for protection but worse in every other aspect. Vinyl is much denser than rubber and thus noticeably heavy. Increased thread count is NEVER an indication of better puncture protection.
Smurfy
Naturist Smurf
- Location
- Smurfette's Kitchen
Look for labels on the tyre side wall. Those with puncture protection typically have a layer of extremely puncture resistant woven material below the tread, such as aramid fibres.
Yellow Saddle
Guru
- Location
- Loch side.
Aramid fibres do not make a tyre puncture resistant.
I'll prove it to you:
Sit down. Take a mat of woven aramid fibre and lay it fat on your thigh. Right or left.
Now take a pen knife and stab your thigh.
Post pictures.
A woven mat cannot prevent punctures. It has to be a solid, tough plasticized strip. Tyres do contain aramid but that's only good for the bead.
No tyre can be puncture proof unless it is solid. They can be made more resistant, that's all, usually a kevlar/aramid/whatever belt under the tread.
It won't work miracles, my Giant MTB tyres are puncture resistant. A flattened metal staple punched right through it no problem at all, nothing will stop something like that.
You can't tell just by looking, unless the manufacturer has labelled them as such.
It won't work miracles, my Giant MTB tyres are puncture resistant. A flattened metal staple punched right through it no problem at all, nothing will stop something like that.
You can't tell just by looking, unless the manufacturer has labelled them as such.
Smurfy
Naturist Smurf
- Location
- Smurfette's Kitchen
Maybe someone ought to tell those people manufacturing aramid gloves, that their product won't protect against discarded needles and sharps. Probably the buyers ought to know too, as they're paying a lot to try and protect people employed in clearing up drug dens.
http://www.turtleskin.co.uk/TurtleSkin-FullCoverage-Aramid-PTS1007XS/
The problem with your stabbing with a penknife example is that it is not at all representative of typical punctures. A great many punctures involve a small shard of glass or flint only 1-2mm long, slowly working it's way through the tyre casing and tube until the air escapes. That is totally different from applying an enormous amount of energy in one hit, as you suggest doing with a pen knife. Your example is the equivalent of running over a piece of wood with a nail in it, and no practical level of puncture protection can ever hope to stop that. To protect against everything, you'd have to have a thick layer, such as in an aramid stab/bullet proof vest, but then the ride quality would be so horrible you may as well use solid tyres. In my experience, anti puncture tyres are remarkably good at stopping punctures from small shards, which is fine, because small shards are the most likely cause of punctures.
Smurfy
Naturist Smurf
- Location
- Smurfette's Kitchen
[QUOTE 3532767, member: 9609"]And of course they just wear through, the following went bang recently, yes litterally went bang, I stopped and was looking for someone over the hedge with a gun, it wasn't until I set off again I worked out what had happened.
Armadillo with 2370miles fitted on the rear. Only one puncture during that time. May be a little observation before riding would have have me a lot of hassle.
[/QUOTE]
Armadillos are pretty good, mine went wonky with bulging sidewalls when the rear was getting fairly worn, so I replaced them, but I never had a puncture while using them.
Armadillo with 2370miles fitted on the rear. Only one puncture during that time. May be a little observation before riding would have have me a lot of hassle.
Armadillos are pretty good, mine went wonky with bulging sidewalls when the rear was getting fairly worn, so I replaced them, but I never had a puncture while using them.
slowmotion
Quite dreadful
- Location
- lost somewhere
It's really simple. All you need is a bucket of water and a small sponge. You carefully wipe the side walls of the tyre and examine them closely. If you can detect lettering that reads "Marathon Plus", it's puncture-proof.
This technique requires real skill that can only be gained by years of experience.
This technique requires real skill that can only be gained by years of experience.
Shut Up Legs
Down Under Member
Marathon Plus tyres aren't puncture proof, just more puncture resistant than most. For some years now, I've done about 15,000km a year on Marathon Plus tyres in all conditions, and they're very good. But not puncture proof. Now, I'd better stop typing, as I've probably exceeded the limit on the number of times I can safely use the word 'puncture' in one thread post. Oops.
Last edited:
Yellow Saddle
Guru
- Location
- Loch side.
[QUOTE 3532767, member: 9609"]And of course they just wear through, the following went bang recently, yes litterally went bang, I stopped and was looking for someone over the hedge with a gun, it wasn't until I set off again I worked out what had happened.
Armadillo with 2370miles fitted on the rear. Only one puncture during that time. May be a little observation before riding would have have me a lot of hassle.
[/QUOTE]
This photo shows clearly why aramid fibres are not ideal for tyre carcasses. Aramid is very abrasive and quickly eats the tyre from the inside out. If you look at this photo, you can actually see the 35 degree cord angle which one normally cannot see in a tyre covered with this much rubber.
@YellowTim . Perhaps my knife example wasn't a good one. I should have suggested an awl.
Tyre punctures generally don't happen like needle pricks or knife cuts. They occur because, as you say, a small piece of glass or sharp metal (typically from damaged steel belt tyre) embeds in the rubber of the tyre and then through repeated turns of the wheel, works itself in between the fibres without cutting them. We know it doesn't generally cut the fibres because the tyre doesn't suddenly bulge after most punctures. Cuts of course compromise the casing's integrity and we see those typical bulges or "broken nose" zig-zags in the tyre.
Here's a picture I've taken from: the website you cited for puncture-resistant aramid (Kevlar) gloves. (http://www.turtleskin.co.uk)
They explain how they attain their puncture and cut-resistant gloves and it is by way of a fine weave. The needle in the picture is 28 gauge (0.3mm). Both the weft and weave here is also about 0.3mm and thanks to Aramid's abrasiveness, it resists shifting and opening up when a needle is jabbed at it. However, massage that needle a little and it goes right through, without cutting a single fibre. Massaging is what happens in tyres but not in sharps disposal. It cuts as well, tiny glass shards shirter than the tyre is thick, slowly work their way right through. Those of us who ride narrow tyres in cities where bottle disposal is by way of breaking the glass in the street, know to inspect our tyres after each ride and remove glass with a sharp object. This glass is almost never visible on the surface but already embedded yet not completely through. Aramid may or may not slow it down.
Like I said, a better material is vinyl but it deadens the tyre. Next time you are in a bike shop, ask to look at vinyl tyre liner. You'll be surprised at the weight. Open the box and feel it. Tough stuff.
As @victor said, even Marathon tyres are not puncture proof, but resist punctures a bit more than snakeskin-thin tyres.
A material that requires a weave in order to create a flat surface will never be a proper puncture protection agent in bicycle tyres where we cannot build up enough thickness.
Armadillo with 2370miles fitted on the rear. Only one puncture during that time. May be a little observation before riding would have have me a lot of hassle.
This photo shows clearly why aramid fibres are not ideal for tyre carcasses. Aramid is very abrasive and quickly eats the tyre from the inside out. If you look at this photo, you can actually see the 35 degree cord angle which one normally cannot see in a tyre covered with this much rubber.
@YellowTim . Perhaps my knife example wasn't a good one. I should have suggested an awl.
Tyre punctures generally don't happen like needle pricks or knife cuts. They occur because, as you say, a small piece of glass or sharp metal (typically from damaged steel belt tyre) embeds in the rubber of the tyre and then through repeated turns of the wheel, works itself in between the fibres without cutting them. We know it doesn't generally cut the fibres because the tyre doesn't suddenly bulge after most punctures. Cuts of course compromise the casing's integrity and we see those typical bulges or "broken nose" zig-zags in the tyre.
Here's a picture I've taken from: the website you cited for puncture-resistant aramid (Kevlar) gloves. (http://www.turtleskin.co.uk)
They explain how they attain their puncture and cut-resistant gloves and it is by way of a fine weave. The needle in the picture is 28 gauge (0.3mm). Both the weft and weave here is also about 0.3mm and thanks to Aramid's abrasiveness, it resists shifting and opening up when a needle is jabbed at it. However, massage that needle a little and it goes right through, without cutting a single fibre. Massaging is what happens in tyres but not in sharps disposal. It cuts as well, tiny glass shards shirter than the tyre is thick, slowly work their way right through. Those of us who ride narrow tyres in cities where bottle disposal is by way of breaking the glass in the street, know to inspect our tyres after each ride and remove glass with a sharp object. This glass is almost never visible on the surface but already embedded yet not completely through. Aramid may or may not slow it down.
Like I said, a better material is vinyl but it deadens the tyre. Next time you are in a bike shop, ask to look at vinyl tyre liner. You'll be surprised at the weight. Open the box and feel it. Tough stuff.
As @victor said, even Marathon tyres are not puncture proof, but resist punctures a bit more than snakeskin-thin tyres.
A material that requires a weave in order to create a flat surface will never be a proper puncture protection agent in bicycle tyres where we cannot build up enough thickness.
Globalti
Legendary Member
[QUOTE 3532767, member: 9609"]And of course they just wear through, the following went bang recently, yes litterally went bang, I stopped and was looking for someone over the hedge with a gun, it wasn't until I set off again I worked out what had happened.
Armadillo with 2370miles fitted on the rear. Only one puncture during that time. May be a little observation before riding would have have me a lot of hassle.
[/QUOTE]
Seems to me there's a serious design flaw in that tyre: you're carrying the extra weight of all that thick rubber yet you've still got the vulnerability of the thin bits between the chunks, which are prone to wear and penetration. Road tyres don't aquaplane so don't need treads and for mixed surface riding a fine "file" pattern is all you need.
Armadillo with 2370miles fitted on the rear. Only one puncture during that time. May be a little observation before riding would have have me a lot of hassle.
Seems to me there's a serious design flaw in that tyre: you're carrying the extra weight of all that thick rubber yet you've still got the vulnerability of the thin bits between the chunks, which are prone to wear and penetration. Road tyres don't aquaplane so don't need treads and for mixed surface riding a fine "file" pattern is all you need.
Yellow Saddle
Guru
- Location
- Loch side.
You will never convince consumes that motorcycle, bicycle and aeroplane tyres don't need tread. I think even the tyre manufacturers have given up and always give us something with tread, even if it is only cosmetic.
On the tyre picture in question, the shallow bits were not abraded away from outside in, but inside out..
Yellow Saddle
Guru
- Location
- Loch side.
[QUOTE 3533140, member: 9609"]Although it is not obvious from the above picture the tyre is delaminating, probably 75% of the casing is loose on the tyre. It is something I really don't like about these tyres they seem to look ok at a glance but then have near catastrophic failures. There was a warning to the above failure that I had ignored, it had started to feel a little lumpy in its last few miles, I had presumed this lumpiness was mud caught between tyre and frame. I must remember to make better inspections of these tyres and replace at any signs of delamination.
so this explains why these tyres seem to delaminate, I have had a few of them and they always seem to fail by shedding the casing, . Here is another picture of the casing coming off armadillo's, this was on the front and had done just over 4000 miles.
[/QUOTE]
Your photos make the point very well. In conventional delamination we have the bond between different rubbers or rubber and casing fail. This isn't delamination in the true sense. This is the aramid weave eating the rubber surrounding it as the tyre flexes at the contact patch. Imagine sandpaper as a layer just beneath a tennis ball's surface and you are squeezing the ball.
I would argue that the tyres in your photos failed long before their tread was exhausted.
so this explains why these tyres seem to delaminate, I have had a few of them and they always seem to fail by shedding the casing, . Here is another picture of the casing coming off armadillo's, this was on the front and had done just over 4000 miles.
Your photos make the point very well. In conventional delamination we have the bond between different rubbers or rubber and casing fail. This isn't delamination in the true sense. This is the aramid weave eating the rubber surrounding it as the tyre flexes at the contact patch. Imagine sandpaper as a layer just beneath a tennis ball's surface and you are squeezing the ball.
I would argue that the tyres in your photos failed long before their tread was exhausted.
Yellow Saddle
Guru
- Location
- Loch side.
Back to this photo for a moment. Consider that the gloves made from this material were sewn together, using needle and thread.
