Tyre age - how much of a concern?

[pfillery]

Really, how much of a concern is tyre age when you are talking about tubed tyres on a series that rearely sees 100km/h? I know some say that 6 years is a good lifespan for tyres but does the same apply to 8 or 14 ply truck tyres with tubes as long as the treads are good?

[33chinacars]

If tyres are in anyway perished dont use them IMHO. Check side walls.
Otherwise BANG.

[JDNSW]

I don't think you can set a specific life in years - deterioration is largely a function of temperature and UV exposure plus the original rubber formulation and construction. All of these vary enormously - for example, tyre life on a vehicle kept in the open in Longreach and used regularly would be may years less than the same tyre on a vehicle in Tasmania, kept in a garage and rarely used. Significant crazing of the sidewalls would be the symptom to watch for, but almost all tyre failures are due to damage or underinflation (not necessarily intentional!), not tyre age. I cannot see that the use of a tube would make any difference - by the time a sidewall is deteriorated enough to leak air, it will be so much weakened that it is dangerous because of this, not the leakage.

Tyres used only at low speed can afford a greater risk of failure because the consequences are less - but I would set "low speed" at closer to 20kph than 100kph!

(The tread deteriorates as well, but it is a lot thicker, and contributes little to tyre strength, which is mostly in the belt and the sidewalls and beads)

John

[gromit]

If they are perished do not use them but you also need to consider that as the rubber compound goes off you lose grip.
When I got my Defender 12 years ago the tyres squealed on roundabouts, fitted new tyres and with new compound came better grip so the squealing stopped. 12 years down the track and I have the same problem (the defender isn't used that much each year).

I'm not saying that you couldn't use older tyres just that you need to be aware that you don't have the same level of grip on the road.

As for 14 ply tyres ..... I don't think you should use these on a Land Rover as they have little flex in the sidewalls and will make the ride very harsh. They could be handy as 'run-flats' because you won't be able to tell whether they are pumped up or not.
Even with my 8-ply RoadTrack Majors you can drop the pressure below 10psi and the tyre looks OK (not even flat at the bottom).


Colin

[Bigbjorn]

It used to be a common habit amongst heavy truck operators to store new tyres and retreads in the shed for a year or so until needed. The widely held belief was that new rubber wore quicker than aged rubber and tyre life was extended by cellaring. I wonder if this is still the case?

[gromit]

It used to be a common habit amongst heavy truck operators to store new tyres and retreads in the shed for a year or so until needed. The widely held belief was that new rubber wore quicker than aged rubber and tyre life was extended by cellaring. I wonder if this is still the case?

That makes sense. When the compound is 'grippier' it would wear more so leaving it to 'harden up' would mean a bit less grip but longer life.

Colin

[crash]

It used to be a common habit amongst heavy truck operators to store new tyres and retreads in the shed for a year or so until needed. The widely held belief was that new rubber wore quicker than aged rubber and tyre life was extended by cellaring. I wonder if this is still the case?
I think that this happens more at the manufacture sight, and the tyres have "cured" before being sold. I have read tyre reviews where they have tested pre production tread patterns and they state that the tyres were still "green" and had terrible wear, but when the production tyres hit the general market and were "cured" properly the tread wear was better than the preproduction "green" tyres.

[slug_burner]

It used to be a common habit amongst heavy truck operators to store new tyres and retreads in the shed for a year or so until needed. The widely held belief was that new rubber wore quicker than aged rubber and tyre life was extended by cellaring. I wonder if this is still the case?

I have also heard this said about farmers who want a harder tyre for resistance to wear and punctures.

[Solly]

I recently had a good quality Michelin tyre that was 5 years old go 'bang', when the side wall blew out... Tyre had done about 65K, had plenty of tread, was inflated correctly, a little weathered but OK.. I though mmmmm luck I was only in town.

Spoke to my tyre man who said these days 4-5 years is the absolute limit on tyre age due to the softer compounds... I knew that, I am a crash investigator ..doh.....

3 weeks later I had to go out to a fatal crash near Timber Creek. Landcruiser had a front driver tyre blowout (clear sidewall blowout)... 4 x 6 year old tyres and all looking in very poor condition, inflation pressures were ok on the 3 others, so guessing that they were ok on the one that blew..

Don't trust any tyre that is more than 5 years old.

[Tombie]

The initial wear on tyres is actually (usually) block compression.

The newer rubber compresses in the first few months making it appear that the tyres have worn quickly.

[isuzurover]

I recently had a good quality Michelin tyre that was 5 years old go 'bang', when the side wall blew out... Tyre had done about 65K, had plenty of tread, was inflated correctly, a little weathered but OK.. I though mmmmm luck I was only in town.

Spoke to my tyre man who said these days 4-5 years is the absolute limit on tyre age due to the softer compounds... I knew that, I am a crash investigator ..doh.....

3 weeks later I had to go out to a fatal crash near Timber Creek. Landcruiser had a front driver tyre blowout (clear sidewall blowout)... 4 x 6 year old tyres and all looking in very poor condition, inflation pressures were ok on the 3 others, so guessing that they were ok on the one that blew..

Don't trust any tyre that is more than 5 years old.

Don't know where your tyre fitter is getting their facts from.

Here is what Bridgestone says:
Aged Tyres (http://www.bridgestone.com.au/tyres/passenger/care/age.aspx)

Aged Tyres- Beware Your Spare

There is some evidence to suggest that aged tyres have an increased likelihood of failure due to exposure to the environment. Ideally tyres should be kept in a cool, dry environment out of direct sunlight and away from electric motors or other sources of ozone. If these conditions are not met a tyre may have an increased chance of failure. It is for this reason that Bridgestone recommend including full size spare tyres in the rotation schedule.

How old is too old?

This is a subject of much debate within the tyre industry and no tyre expert can tell exactly how long a tyre will last. However, on the results of experience many tyre companies, including Bridgestone, warrant their tyres against manufacturing and material defects for five years from the date of manufacture. Based on their understanding a number of vehicle manufacturers are now advising against the use of tyres that are more than six years old due to the effects of ageing.

So if bridgestone and most others warrant 5 years, and say you should think of changing them at 6, I cannot see how 4-5 is the limit?

As JD posted above, it depends much more on condition than any absolute value. I suspect conditions in the NT are harsher on tyres than down south.

I would bet that heavy vehicle tyre carcases are used for retreading at > 6 years old if they are free from visual defects?

[Tank_JR]

silly me bought an old bedford truck had 20 year old tyres on it drove it about 80 ks and they didnt let go but in saying that they where 20 inch truck tyres probably a bit better then LT tyres

[Tank_JR]

I don't think you can set a specific life in years - deterioration is largely a function of temperature and UV exposure plus the original rubber formulation and construction. All of these vary enormously - for example, tyre life on a vehicle kept in the open in Longreach and used regularly would be may years less than the same tyre on a vehicle in Tasmania, kept in a garage and rarely used. Significant crazing of the sidewalls would be the symptom to watch for, but almost all tyre failures are due to damage or underinflation (not necessarily intentional!), not tyre age. I cannot see that the use of a tube would make any difference - by the time a sidewall is deteriorated enough to leak air, it will be so much weakened that it is dangerous because of this, not the leakage.

Tyres used only at low speed can afford a greater risk of failure because the consequences are less - but I would set "low speed" at closer to 20kph than 100kph!


(The tread deteriorates as well, but it is a lot thicker, and contributes little to tyre strength, which is mostly in the belt and the sidewalls and beads)

John

A tube would help as the air destroys the tyre thats why some tyre shops are using nitrogen

[gromit]

A tube would help as the air destroys the tyre thats why some tyre shops are using nitrogen

I thought that nitrogen was only used to increase their profit margins

http://www.aulro.com/afvb/d3-d4-rrs/124704-nitrogen-infllation-tyres.html




Colin

[JDNSW]

A tube would help as the air destroys the tyre thats why some tyre shops are using nitrogen

Examination of any old tyre will show that it is in a lot better condition inside than outside. The effect of air on rubber is very minor compared to the effects of heat, UV and ozone (and there will be neither UV nor ozone inside, whether there is a tube or not, perhaps more heat, as there is less cooling).

Nitrogen as an air replacement has no measurable effect on tyre life in itself. Any slight improvement is because the nitrogen is dry, whereas the air has a small quantity of water vapour, but this affects the behaviour with heating rather than any direct effect on the rubber and reduces the fire risk in racing. The only measurable effect of nitrogen as a filler for road tyres is to reduce the load by lightening the driver's wallet.

John

[Lotz-A-Landies]

I think we need to introduce another aspect to consider. Most 20 year old tyres on a Bedford truck and series Landies will be rag ply tyres while the modern tyres Bridgestone and Michelin are discussing are radial often steel belted tyres.

Rubber is a porous substance that will allow in moisture. If you have a vehicle sitting on the grass for long periods the moisture can get into and rust the steel belt, de-laminating the belt from the radial ply. As the tyres return to the road the de-laminated belt and tyre work against each other creating a point of heat and increasing the risk of failure.

So if you have a vehicle with radial tyres particularly if they have been sitting on dirt, then 5 or 6 years is probably too old.

IMHO If the series Landy with cross ply (or bias ply) tyres has been sitting in the shed and only goes to car shows then the tyres can probably be much older.

Diana

[JDNSW]

....

Rubber is a porous substance that will allow in moisture. ...

Diana

As a general statement, I would take issue with this! Rubber is the material par excellence for seals whether for water or air, and in the case of tyres we expect it to keep air in indefinitely. As an example, some years back I acquired a Landrover chassis at a clearing sale. It had not, I would estimate, been moved for at least ten years. Yet the two radial tyres, fitted tubeless, still had over 20psi in them (two tubed crossplies were flat).

So I have to ask, if the rubber can keep air in, how does it let water, or even water vapour in? Of course, if the rubber covering of the belt is already deteriorated with cracks as far as the steel belt, it is a quite different situation.

John

[Tombie]

Rubber is not porous!

The exceptions would be closed cell neoprene (wet suits)

Only tyres with poor casings or cracks would be porous.

[123rover50]

All this is very disturbing. I have 8 of 900x16 Michelin for the 6x6 FC that are now nine years old with only 40,000 kays on them I suppose I will have to replace them now.

[series3]

.... And maybe I should replace the antiquated Firestone Haulage Lug sitting in the back tub as a spare! It would have to be at least 30 years old

Sam

[DEFENDERZOOK]

ok......nitrogen is used in tyres because it doesnt change pressure with temperature like air does.....
it doesnt expand and increase pressure when the tyres heat up on long highway trips.....


ive got old tyres on the back of my mazda......they would have to be at LEAST 20 years old......
odd size....225 60 R13.....no longer available.....so i bought what i found.....
they did not have much traction when i first fitted them......as i found out on a few corners......
but my driving style soon softened them up and increased the grip.....so much so that i actually noticed the difference.....

same corner......same car.....everyday......and i can take it faster and faster each day.......and each day i needed less and less opposite lock......



then....on the other hand......there was a mix up at work.......where a set of brand new tyres were fitted to a 4wd.....off he went only to come back a week later
making lots of noise......him.....not the tyres.....he had a blowout on the way to canberra from sydney.......
upon inspection...we found that the tyres were 12 years old when fitted.....they were sitting in stock in a shop which closed down......and were
transferred to another store for a few more years......before we got them.....
no one bothered to check the age of them......and yes.....they were not a very popular size........
we assumed it was old age that caused the failure........but it could have simply been overheating from a puncture.....
theres no way of telling......so we fitted five new fresh tyres under warranty....




in plain english........there is always a risk you take.......

the risk is pretty much governed by each individuals wallet......i know for a fact that i cant afford new tyres for my fender......
im running a really old set of bfg muddies only because i got them for free.....
there are visible signs of perishing on the outside......look just fine internally.....and so far.....i have been lucky and not had any problems with them......


then again......ive seen brand new tyres delaminated.......

[JDNSW]

ok......nitrogen is used in tyres because it doesnt change pressure with temperature like air does.....
it doesnt expand and increase pressure when the tyres heat up on long highway trips.....
...............


This may be the reason it is used, but since air is 80% nitrogen, and all gases, including both nitrogen and oxygen (which makes up almost all of the remaining 20%) follow the same gas laws with pressure proportional to absolute temperature, the use of nitrogen for this reason reflects the sad state of science education in Australia rather than reality.

Any difference in pressure increase will reflect water content rather than what gas is involved - water does not follow the gas laws over this temperature range, because over the temperature range involved there is likely to be a phase change from liquid to gas.

John

[rick130]

[snip]

Any difference in pressure increase will reflect water content rather than what gas is involved - water does not follow the gas laws over this temperature range, because over the temperature range involved there is likely to be a phase change from liquid to gas.

John

Bingo.

For a while dehydrated air was used in F1 tyres, (and may still be ?) much cheaper than nitrogen.

I used dehydrated air for a long time in race cars and found no difference when I used nitrogen.

[Dougal]

I thought that nitrogen was only used to increase their profit margins

http://www.aulro.com/afvb/d3-d4-rrs/124704-nitrogen-infllation-tyres.html

Colin

Indeed it is. You can spot a sucker by the green caps on their tyres.

What really concerns me is people who have paid for nitrogen will drive on underinflated tyres rather than top them up with normal air.:(
Sometimes having to wait days until they can find another tyre shop with nitrogen.

Then you have the people who don't check their tyre pressures because nitrogen doesn't leak out as fast.:eek:

I had one tyre fail recently. It was a retread that was around 20 years old. One of my mud tyres which cracked across the casing and chaffed through the inner tube.

[Tank_JR]

Examination of any old tyre will show that it is in a lot better condition inside than outside. The effect of air on rubber is very minor compared to the effects of heat, UV and ozone (and there will be neither UV nor ozone inside, whether there is a tube or not, perhaps more heat, as there is less cooling).

Nitrogen as an air replacement has no measurable effect on tyre life in itself. Any slight improvement is because the nitrogen is dry, whereas the air has a small quantity of water vapour, but this affects the behaviour with heating rather than any direct effect on the rubber and reduces the fire risk in racing. The only measurable effect of nitrogen as a filler for road tyres is to reduce the load by lightening the driver's wallet.

John

you say ozone will affect the tyre on the out side well doesnt that mean pumping air "ozone" as you would call it in to it do the same thing ?

[JDNSW]

you say ozone will affect the tyre on the out side well doesnt that mean pumping air "ozone" as you would call it in to it do the same thing ?

Any ozone that is pumped into the tyre will react with the inside surface of the rubber, and then there will be no more ozone inside until next time you change the air in the tyre. On the outside, the air in contact with the tyre outer surface is continually changed, so that the ozone (which is in a very small proportion anyway) is continually refreshed. The major factors involved in deterioration of tyres are temperature and UV light - ozone affects rubber, but the amount normally present in air is very small - measured in nanomol/mol, or to put it another way, parts per billion. It arises from the interaction of sunlight on air with some pollutants such as nitrogen oxides or from the presence of strong electric fields from discharges such as lightning or other sparks. None of these processes are present inside tyres!

John

[Bushie]

Nitrogen in aircraft tyres (http://www.boeing.com/commercial/aeromagazine/aero_05/m/m03/index.html)
I'd consider this a fairly authoritative source.



........................Boeing has received reports of three confirmed cases and other suspected cases in which a wheel/tire assembly exploded when the oxygen in air-filled tires combined with volatile gases given off by a severely overheated tire. In one case, the tire became overheated as a result of a dragging brake, and the wheel/tire assembly exploded when it reached the auto-ignition temperature. In another case, a wheel/tire assembly explosion in the wheel well during flight was suspected in the catastrophic loss of one airplane. A similar explosion caused severe damage to two others.
As a result, the U.S. Federal Aviation Administration issued Airworthiness Directive 87-08-09 requiring that only nitrogen be used to inflate airplane tires on braked wheels. However, tires may be topped off with air in remote locations where nitrogen may not be available if the oxygen content in the tire does not exceed 5 percent by volume.

[PhilipA]

All this is very disturbing. I have 8 of 900x16 Michelin for the 6x6 FC that are now nine years old with only 40,000 kays on them I suppose I will have to replace them now.

As long as they do not have cracks on the sidewalls do not worry.
I have run 10 year old tyres with no problems. Actually 2 years ago I replaced a set of BFGs that were pre2000 when the dates started to be stamped on the tyres, only because they began to get cracks around where the tread meets the wall, and that was just after a trip to the Flinders etc.
I bought a set of performance tyres for my BMW a few years ago and found they were six years old after I bought them. BUT they were excellent.

FYI, many of the performance tyres sold cheaply by places like St George tyres in Sydney are Japanese imports which are very old. My guess is that they bring them in as used, but as they are stored out of sunlight and in their wrapping they are fine by me.

I have some old original pattern Michelins under the house for my trailer . How old are they?
Regards Philip A

[Dougal]

Nitrogen in aircraft tyres (http://www.boeing.com/commercial/aeromagazine/aero_05/m/m03/index.html)
I'd consider this a fairly authoritative source.



You've got to be hot enough to make the tyres gas-off first. That is very very hot.

[rick130]

You've got to be hot enough to make the tyres gas-off first. That is very very hot.

And hotter than any race car has ever achieved I'd bet, including those with carbon/carbon brakes.

[JDNSW]

And hotter than any race car has ever achieved I'd bet, including those with carbon/carbon brakes.

Also worth noting is that the auto ignition temperature will depend on the partial pressure of oxygen inside the tyre - and it should be noted that tyre pressures on heavy aircraft are very high compared to those used on road vehicles - 200psi + on jet aircraft.

John

[rick130]

Also worth noting is that the auto ignition temperature will depend on the partial pressure of oxygen inside the tyre - and it should be noted that tyre pressures on heavy aircraft are very high compared to those used on road vehicles - 200psi + on jet aircraft.

John

vs below 20psi hot on an F1 car, IIRC it's around 1.1 bar/15psi.

Oh, and FWIW dehydrated air is still used in in F1 as it was when I was heavily involved in racing in the nineties, not nitrogen, or at least it was up to 2008.


Bridgestone fills their Formula One tyres with dried air - normal air which has been processed to remove the moisture content. Formula 1 (http://www.formula1.com/news/features/2008/5/7777.html)