Tyres

[Jeremy]

This assertion that tyre strength becomes unsafe after 6 years isn't supported by the chemistry of the materials in tyres at all - it sounds very much like total bullshit promulgated by tyre manufacturers to sell more tyres.............

Let's look at the materials commonly used in tyres, and their age-related degradation characteristics:

The carcass is a rubber compound, that will suffer from oxidation and UV degradation with age. However, this degradation usually happens from the outside inwards, so is easy to spot from a good visual inspection. Its also very dependent on the actual formulation of the compound, so life will vary massively both with exposure conditions and compound.

Next, let's look at the internal tyre structure. There will be steel wires, either just as bead reinforcement or embedded in the carcass to stabilise the tread section under load. Provided that the steel remains embedded in the rubber compound and isn't exposed to the air, then its calendar life will be very long, certainly many tens of years. If the carcass uses steel tread and sidewall reinforcement then it may fatigue with use, but this is likely to be well in excess of the rubber compound normal wear limit.

The tyre may use synthetic fibres, such as nylon, polyester or even Kevlar as internal reinforcement. These can degrade with UV exposure and heat, but have a very, very long calendar life if protected from UV exposure and excessive heat. Inside a tyre carcass their calendar life would be close to infinite.

If tyres are protected from sunlight, kept properly inflated and, perhaps, lifted off the ground when not in use for long periods, then they will easily last for ten to twenty years or more. There are reasonably high numbers of veteran and vintage cars running around quite safely on tyres that are much, much older than this.

Jeremy

[ChrisB]

Bit like the way they waffle on about changing caravan tyres every x number of years

I always use common sence, if it looks bad it IS

ChrisB

[andylaurence]

Bit like the way they waffle on about changing caravan tyres every x number of years

That's because caravans are often to be found scattered across the road in small pieces after a tyre blow-out. I suspect it's down to the fact that they sit dormant for 51 weeks, then travel a few hundred miles in one week. As for the age of tyres, whether they cause a blow-out or not, once a tyre gets to 6 years old, it's not going to give much grip. Given that the only thing that stops you in an emergency is the grip of the tyres, I'd stick to new rubber. I ran a set of 2004 Bridgestone performance tyres at an AutoSolo a couple of years ago. I was almost dead last from lack of grip. I used a set of <2 year old Michelin Energy tyres at an event this year and did quite well.

[tim.strutt]

Just thought I'd post these to add to the debate...

http://www.rospa.com/roadsafety/advicea ... ation.aspx

http://menmedia.co.uk/manchesterevening ... sured.html

...also anyone have a GM or Ford owners handbook (post 2006) as I've been led to believe that they post a specific warning about tyres over 6 years old.

[Jeremy]

Just thought I'd post these to add to the debate...

http://www.rospa.com/roadsafety/advicea ... ation.aspx

http://menmedia.co.uk/manchesterevening ... sured.html

...also anyone have a GM or Ford owners handbook (post 2006) as I've been led to believe that they post a specific warning about tyres over 6 years old.

The MG accident report indicates "wobbling" prior to the crash, which is quite likely to have been caused by a bulge in the tyre, which may or may not have been age related. The driver seems to have deliberately ignored the warning and carried on until the tyre failed, according to the report. However, the same thing could have happened with a tyre that was nearly new, as, if it was a side wall bulge then it was most probably a consequence of physical damage (kerbing, for example) rather than ageing.

The RoSPA advice seems sensible and doesn't actually stipulate a hard lifetime limit, but makes recommendations that are, because of the nature of the organisation making them, likely to be conservative. Overall, what they say pretty much supports the points I made above about the variability in tyre compound ageing from differing exposure conditions. If you were to seal tyres up away from light and exclude oxygen they would probably last for decades. Interestingly, this is a far greater problem on other rubber parts. My background is aviation and degradation of natural rubber parts is a significant problem. One thing that I've used that has more than doubled the life of natural rubber parts that are exposed to air is Halfords Rubber and Nylon lubricant in an aerosol can. I'm not advocating its use on tyres, but if you had some tyres stored and wanted to slow down degradation then I think this stuff would be excellent. Obviously you wouldn't want to get it on the tread, but carefully applied to the side wall (the area most prone to degradation usually) it would almost certainly reduce the oxidation rate. I used it very successfully on things like carburettor AV mounts, which untreated have a life of around a year to 18 months before they start to crack and need replacing. Regularly treatment (every 6 months) with the Halfords stuff extended their life out to three or four years.

[ChrisB]

Bit like the way they waffle on about changing caravan tyres every x number of years

That's because caravans are often to be found scattered across the road in small pieces after a tyre blow-out. I suspect it's down to the fact that they sit dormant for 51 weeks, then travel a few hundred miles in one week.

..........and nothing to do with planks who dont know how to load or drive with said attached caravan
A flat or even a blow out on a trailer/caravan is highly unlikely if at all likely to cause it to end up looking like match wood , I've had punctures on trailers and seen the aftermath of the odd blow out on a caravan and the worse it seems to do is distroy the dam wheel arch and make a bit of a mess of the side of the caravan due to bits of tyre flailing about inside the wheel arch.

Where as a poorly loaded trailer/caravan is what WILL cause not only the tralier caravan to end up being scattered but the tow car too , infact only a few weeks back traveling to Glasto along the A303 some poor soul had their van and car completely totalled over both carriageways in the classic "it got away from him" area, bottom of a reasonabley steep hill and judging at the amount of "stuff" strewn about I suspect loading was the issue.

As for the age of tyres, whether they cause a blow-out or not, once a tyre gets to 6 years old, it's not going to give much grip. Given that the only thing that stops you in an emergency is the grip of the tyres, I'd stick to new rubber. I ran a set of 2004 Bridgestone performance tyres at an AutoSolo a couple of years ago. I was almost dead last from lack of grip. I used a set of <2 year old Michelin Energy tyres at an event this year and did quite well.

But your comparing chalk and cheese, at an AutoSolo event your pushing both man and machine relatively hard, EV's or at least mine dont just dont have that sort of perfomance


ChrisB

[andylaurence]

Bit like the way they waffle on about changing caravan tyres every x number of years

That's because caravans are often to be found scattered across the road in small pieces after a tyre blow-out. I suspect it's down to the fact that they sit dormant for 51 weeks, then travel a few hundred miles in one week.

..........and nothing to do with planks who dont know how to load or drive with said attached caravan
A flat or even a blow out on a trailer/caravan is highly unlikely if at all likely to cause it to end up looking like match wood , I've had punctures on trailers and seen the aftermath of the odd blow out on a caravan and the worse it seems to do is distroy the dam wheel arch and make a bit of a mess of the side of the caravan due to bits of tyre flailing about inside the wheel arch.

Where as a poorly loaded trailer/caravan is what WILL cause not only the tralier caravan to end up being scattered but the tow car too , infact only a few weeks back traveling to Glasto along the A303 some poor soul had their van and car completely totalled over both carriageways in the classic "it got away from him" area, bottom of a reasonabley steep hill and judging at the amount of "stuff" strewn about I suspect loading was the issue.

Yes, loading is more of a problem, although tyres can be the trigger and loading the catalyst. Either way, there's a disproportionate number of caravans & trailers with tyre blow-outs.

As for the age of tyres, whether they cause a blow-out or not, once a tyre gets to 6 years old, it's not going to give much grip. Given that the only thing that stops you in an emergency is the grip of the tyres, I'd stick to new rubber. I ran a set of 2004 Bridgestone performance tyres at an AutoSolo a couple of years ago. I was almost dead last from lack of grip. I used a set of <2 year old Michelin Energy tyres at an event this year and did quite well.

But your comparing chalk and cheese, at an AutoSolo event your pushing both man and machine relatively hard, EV's or at least mine dont just dont have that sort of perfomance

ChrisB

My point was that old tyres have substantially less grip than new tyres. That's important, whether you're competing or trying to get somewhere safely. Your ability to stop and turn is determined by how much grip you get from the tyres. It's the biggest factor. So, if you have to do an emergency stop or take other evasive action, you'll have a much better chance with decent tyres. I don't think you can dispute that. From my point of view, I'd rather replace some old tyres before they're worn than worry about having an accident because my stopping distance is 50% greater than it should be. In fact, that's exactly what I did - I replaced 4 year old tyres because they didn't produce much grip, having hardened significantly over time.

Cheers,
Andy

[ChrisB]

Thats fair enough Andy

Each to there own, me being a cheap skate gets every ounce of life from anything I own

Lots of folk hate remoulds or un branded tyres, I personally like them, yes I've found some of them not to have as much grip as say a branded tyre but then if you've only got £30 per tyre to spend then you have to take whats available
The current set on my old diesel are totally pants in the wet, but then when compared to the ones on my wifes company Vectra they are £100 EACH cheaper but then they are far more gripper.

ChrisB

[tim.strutt]

Hi Jeremy, thnx for the reply, it looks like this six year rule is as contenious an issue as ever it was when I first read of it in 2004/5

I've finally located what I believe to be a contemporay version of the recommendation I read all those years back (although I think mine wasin the form of a technical service bulletin and from inside a firewall)

http://goliath.ecnext.com/coms2/gi_0199 ... -Ford.html

I'll freely admit I don't have anywhere near the depth of industrial experience as your good self, just some real personal experiences of tyre related incidents, and probably of having read too much - but the six year rule I still hold has more to it than an urban myth or a warning purely for the uninitiated.

I have to agree strongly with Andy about tyres going of. I managed to total a pristine 1995 civic (<18k miles) back in 2003 the first time I took it out on its original tyres and the heavens opened up. If it wasn't for a witness who backed up my claim to have slowed with no problems prior to manouvering, and of being doing significantly less than the 40mph limit when the rear end behaved like it was on ice when I started to proceed accross the white line I'd have six points on my licence as well.

A six year rule is recommended by Ford and I beleive GM even now, while contentious, (for all the right reasons that have been suggested), I've not read anything that makes the case to allow me for one to disregard the six year mark, as a rule - especially if you don't know the history of the tyres, and is also the reason why I never buy second user tyres
(note the properly stored six year vs abused 1 year old tyre comment, but if you don't know the history)

Btw, while checking tyres and seat belts for cuts etc is part of the MOT, if in the mean time you find that there is a cut in the edge of your seat belt, from say being trapped in the lock when closing the door, replace them, as the strength from the belt is in the edges - some 90+%, allegedly .... Then again theres a ten year rule (according to research from Australia in 2002) for when you replace outwardly perfect but againg seatbelts...

Kindest regards & safe motoring,

Tim.

[ChrisB]

Suppose we better not mention replacing Airbags after X number of years

ChrisB