do tyres most commonly wear out or fail in another way?

[Brucey]

I recently attended a lecture given by an expert in the field of graphene research. He opined that Vittoria use graphene in some of their tyres because it confers better wear properties on a given thickness of tread rubber. I am sceptical about that, and have not seen any good research that suggests that this is really the case. If it were so, then maybe they would be using it in car, aircraft and motorcycle tyres too. I harbour a lurking suspicion that the real reason they use it is perhaps something different to that.

But anyway, it got me thinking, that bicycle tyres 'wear out' is not the first 'problem' that I would try and cure. The reason I say this is that the number of truly worn out tyres I see is small by comparison with the number that fail for other reasons, carcass damage (eg cuts through the tread) and sidewall cracking being common culprits. A good portion are run underinflated on the rear of a sit-up-and-beg bike and they (weirdly) often wear at the tread edges and not so much in the tread centre. Often a good front tyre is ditched because it does not match a new rear or something.

Also, standards by which tyres are judged to be 'worn out' appear to vary enormously; a chum donated me his 'worn out' conti sport contacts recently; the shallow file pattern had just started to wear smooth in the centre of the rear tread and the front tyre looked almost like new. There were two small cuts in the rear tyre which my chum was also concerned about. Neither looked that bad to me, since they were small and had severed few if any of the cords in the carcass. I'd have pulled the one tiny flint I found out of the rear tyre, swapped the front for the rear and carried on the same distance again, probably.

So do folk consider that tyre wear is a big deal? Or do they find that tyre life is usually limited by carcass damage or 'something else' ? When are tyres considered to be 'worn out'? Does this vary a lot with the duty that the tyres see, the judgement of the rider, or the tyre type, or all of the above?

I will own up to using some tyres (with nylon carcasses) long after others would have binned them. The rubber may start to crack, but the carcass does not appear to be liable to fail via rotting etc as it does in many other tyre types. On the rear of a bike that is used for utility purposes, it seems to work OK.

cheers

[andrew_s]

I retire tyres when I consider them worn out - i.e. when I can see the casing cords through the tread, when they've started to go fluffy in the middle, or when I've had a second or third puncture over a short period of time and the centre of the tread feels thin to my fingers (eg a ridge either side of the centre).
I mostly ignore minor cuts, on the grounds that I'd have to have booted anything major, and most cracking on the grounds that it doesn't affect the casing.
I did retire a tyre on cracking grounds the other day, but that was on a non-dynohub wheel that I'd probably last used 17 or 18 years ago. This link is an example of how cracked one of my tyres has got without any immediate sign of failing (Photobucket warning).

I will swap an old tyre for a new one before a tour, but the old one will usually go back on when I remember it.

I've seen a number of people say they've retired tyres because of cracking that looks to me like the reinforcement against rim hook wear starting to separate - Contis shed threads, other brands start to show what looks like a crack.

I'm of the opinion that Vittoria use graphene because it's the latest high tech buzz word - i.e. for marketing reasons.

[iandriver]

I tend to use somewhere in the middle tyres with a blend of speed and puncture protection, accepting the odd puncture as worth it. I only use M+s in the depth of winter. I find the rate of puctures increases as the tyre wears with the inbetweens, so I tend to bin them when I get fed up with the punctures. I often cut them through to see the cross section. What looks like a small flat track along the centre is often a severe loss of rubber depth. I gave up on Gatorskins many years ago because of sidewall failures.

[whoof]

Graphene is a sheet (x/y plane) of carbon that's a mono-layer (or a close as you can get it ) of atoms in the z-direction.

One early method of making it was sticking a piece of tape to a pencil 'lead' and pulling it off, hoping that the layer of surface atoms would be pulled off. The thickness of a sheet of graphene is about 1 nm (one millionth of a milometer). It has some very interesting electric properties but 1 nm of any material isn't prevent wear whether that's due to friction, cuts or anything else.

As to what does for tyres; for me it's either that they have worn beyond some makers wear point or you can start to see the carcass or they have significant nicks or cuts in them usually due to having ridden through glass.

[amediasatex]

The reason I say this is that the number of truly worn out tyres I see is small by comparison with the number that fail for other reasons, carcass damage (eg cuts through the tread) and sidewall cracking being common culprits.

I'd tend to agree with this, but I think it's a combination of both and also use dependant, with a dose of 'type of tyre' style caveats in there too.

The only tyres I manage to wear out in terms of actually wearing all the tread off are on bikes that do high mileage in a short period of time, or use actual race tyres that wear quickly. That is to say if the lifetime of a tyre is to be 5,000 miles (an arbitrary number) then you might have to do those 5,000 miles relatively quickly, before you might start running into issues with carcass damage or degradation. I don't think it's jsut about miles if you know what I mean?

Winter vs summer use is relevant too, my tyres get torn to shreds in the winter with all the detritus on the roads, in summer they pick up a lot less damage over the same number of miles.

An example being Panaracer Pasela skinwall tyres, the pair on my town bike are about 18months old, probably only done ~3000 miles as it's a short trip bike, and there is little in the way of appreciable tread wear but I'm contemplating replacing the rear at least. The sidewall has the tell-tale hatching and is visibly distressed, they have some life in them yet but the carcass is obviously damaged. Probably a result of running them a little soft (for comfort) and the wildly variable loads this bike carries. One day it might just be me, another it'll be panniers and a trailer. I'm not diligent enough to adjust the pressures mid-trip so sometimes it's ridden in 'sub-optimal' ways. It's a price I'm willing to pay though for various features.

On the other hand though, my audax and club bikes burn through tyres at quite a rate, I was getting through a rear every 1500 miles or so, which can be ~3 months or so.They are actually wearing out the tread, but structurally still fine. Obviously they're a smaller tyre, and the ones I was using are fairly fast wearing anyway, but again, a price I'm willing to pay for their performance.

My general training bikes sit in the middle, and probably are 50/50 split between tyres that wear out and tyres that get damaged, I'm not fussy about matching tyres, and in fact often deliberately don't. I'll often run a sturdier cheaper tyre on the rear and something lighter and posher on the front, that way I either equalise longevity between ends, or else replace the cheaper rear a bit more frequently.

I can;t remember the last time I actually wore out an MTB tyre They invariably die a horrible death being shredded to pieces or being worn to the point of not working properly due to specific bits of tread being worn, even though there's plenty of 'other' tread left. They're retired to this point despite not being worn out in some people's eyes, but once their performance has degraded beyond acceptable levels that's worn out for me.

The holy grail is of course a super supple light weight carcass tyre, with a nice supple thin tread, that also lasts forever, has good grip and sidewalls that don't perish.

[PH]

I wear them out, either down to the canvas or until there's plenty of the puncture layer showing*. Not always on the wheel they started out on, I like a decent tyre on the front of any bike and all wheels I'm likely to be 100's of miles from home on. It helps to have all bikes running similar sizes, if I didn't I'm not sure what I'd do with a well worn but not worn out tyre, probably bin it.

*The only exceptions to this have been when I ran Panaracer Paselas about a decade ago and suffered a couple of sidewall failures and a conti GP4S that developed a bulge (and was replaced by the shop)

[Vorpal]

In tyres that are near their end of life, I expect that it's 6 to one, half dozen of t'other.

Wear will make tyres moer susceptible to other failures such as sidewall damage. I am certain that if you looked at the 'bathtub curve' for tyres, you would find many specific failure modes increasing as if from wear, even when they were theoretically 'random', such as punctures.

So, I consider it one and the same. A tyre is worn out if I can see canvas, if it has significant flat surfaces where there used to be tread, or if I get more than 2 punctures within a week on the same tyre and cannot find any foreign object or something else wrong. This has only ever happened to me on tyres that were looking well worn.

As for Vittoria and graphene goes, Vittoria are, as far as I know, the only company using graphene in tyres. Other companies feel that other materials are better. IMO, it does have some advantages in terms of wear versus weight & rolling resistance. There are a number of technical papers of the advantages of the physical characteristics of graphene. But one area where I don't feel it has any advantage, and may have a small detriment is friction, which of course translates to grip.

My opinion is that graphene does contribute to tyre life and probably makes up some of the difference in life between Vittoria tyres and some other popular brands.

We canæt have the best wear characterisitcs, the best rolling resistance, and the best grip all in the same tyre. You only get to pick two.

Personally, I'd rather replace tyres a bit more often than give up even a small percentage of the traction performance.

[bovlomov]

For practical purposes, what counts as 'worn out'?

For me, it would be regular punctures, or loss of grip. Tyres have to be very bad - and very bald - for either of those things to happen. I haven't changed the tyres on my regular bike for years, and I neither skid nor have punctures. They'll be OK for a while longer.

[tim-b]

Hi

...underinflated...often wear at the tread edges and not so much in the tread centre

This is a classic wear pattern for a car tyre, although car tyre sidewalls are possibly proportionately stiffer than a cycle tyre
Regards
tim-b

[robc02]

It's not very often I wear a tyre tread down to the carcass. Usually they are replaced because of carcass damage indicated by bulging, or because of cuts deep and long enough to expose the carcass.

[Mattyfez]

I wear tread out on my mountain bike much more than they fail structurally from damage /fatigue.
But they do have a soft tread so tread wear is accelerated on a hard surface. Usually replace when the centre knobs are about 1mm or so.

I don't think graphine would be helpful in the tread in my case as it would probably give less grip.

As a structural part of the tyre beneath the tread though or in the side wall I can image it could be useful as a weave, puncture resistant /light?

[foxyrider]

I've got more than a few used tyres in my 'emergency' use pile, tyres that reading above many of you would still be riding.

The best bike uses GP400sII's which are replaced annually at least regardless, sometimes more often depending on how much riding I do on it. (it had a second set fitted for my tour last year for example.)

The Chameleon gets new tyres at each major service regardless, the other bikes will have new tyres for a tour or as required. For me the latter means, two deflations, or having developed a flat top. TBH not many tyres go that way as i've replaced them before that stage. Of course over the years i've had to replace tyres with just about every failure you can imagine, emergency skid, failed side walls, worn through, wobbly Wolbers, tube explosions, big cuts, cracked sidewalls etc, etc.

These days I rarely suffer from the puncture fairies, one this year (TD), one last year, two the previous, none the year before that. Indeed my single use of tubes must also affect this statistic. I used to wear tubulars out but at the same time the Michelins on my other bike seemed to last forever!

Is there a market for part worn tyres like there is for cars?

[gaz]

Few of my tyres wear out before they fail in some other way, usually sidewall failure of some kind.

I am beginning to feel that my winter studded tyres have worn out. The last few winters have seen very few frosts, never mind icy conditions. I still ride them on a just in case basis, it's mostly carbide studs on tarmac.

The studs did not seem to bite into the ice the one day we had some last winter. It's possible the tyres may have simply been over-inflated, I'll see what this winter brings.

[Brucey]

once of the arguments for the use of Graphene is that the lattice is phenomenally elastic in the plane; it is claimed that it will stretch elastically by 25-30% or something like that. If so its use a filler in rubber may have something going for it.

cheers

[gbnz]

So do folk consider that tyre wear is a big deal? Or do they find that tyre life is usually limited by carcass damage or 'something else' ? When are tyres considered to be 'worn out'?

My tyres invariably wear out, normally being binned after running for a few thousand miles or more with the puncture protection strip and/or inner fibres becoming ever more visible. The only exception to this, have been;

1. This year; where I had my first ever tyre blow out (On a rear tyre where I'd been able to see the puncture protection strip, but was quite clear that the tyre would last another couple thousand miles-it lasted perhaps a week)
2. This year; where 3 No. brand new Schwalbe Deltta Cruiser Plus had huge sidewall cracks from day one (Nb. One had 8-10mm bulges in the sidewall after a minimal amount of use)
3. Road (Racing) 20-23mm tyres, where I'm always dubious about whether they're safe to use or not, given that they're thin and lightweight from day one.