Safe to use very old spare tyre ??

Mandrake · Unread post by **Mandrake** » 06 Feb 2006, 20:40

Just to be a dissenting voice in the consensus here, I've seen more than one tyre engineer reported as saying that the rubber in tyres exposed to the elements (heat, sunlight, humidity, etc) deteriorates over time independant of mileage, and that even if there is plenty of tread left they don't recommend using a tyre that is more than about 7 years old as the rubber carcass can have deteriorated significantly.

Of course, they could just be saying that because they sell tyres, so take it with a grain of salt, but it should be remembered that rubber can and does perish, its only a matter of how quickly, depending on the environment. (Just look at the Xantia strut top rubbers for proof of that)

Strangely enough I have a set of tyres on my Daihatsu Charade which were fitted new in 1998 and the car has done very low mileage since then, (basically a "spare car") and there is still a lot of tread on them, but the rubber is looking decidedly fatigued - lots of tiny hairline cracks all over the tyres.

The car has spent its whole life outdoors and has never been garaged, so is therefore exposed to the elements. I can't help wondering whether the underbody location of the spare tyre on a Xantia counts as "outdoors" as far as the elements getting at the tyres and perishing the rubber is concerned...

Chances are that the tyres of a car that spends a lot of time indoors in a garage would last longer than one that lives outdoors, so the 7 year figure is probably a worst case scenario, and many tyres may last longer than that.

Regards,
Simon

DerekH · Unread post by **DerekH** » 06 Feb 2006, 20:52

For my sins I am a caravanner! javascript:emoticon(':roll:')
Rolling Eyes

The caravan club make it very plain that on caravans you should not use a tyre older than 5 years but MUST NOT use a tyre older than 7 years. This applies to unused spares too.

For what a tyre does and for what it costs there really is no argument over this.

Derek

Unread post by **Peter.N.** » 06 Feb 2006, 21:20

Well, I can only speak as I find and in 50 years and probably 1,000,000 miles of motoring, I have never had a tyre blow out, I have had them fairly suddenly deflate, and that can happen any time if you run over something sharp enough. We used to run tyres down to the canvas (before the tyre laws or speed limits) as tyres were expensive relative to income. As tyres are now relatively cheap I can appreciate the case for replacing them, but old habits die hard!

PowerLee · Unread post by **PowerLee** » 06 Feb 2006, 21:29

Sorry but I value my LIFE more then the cost of replacing a sodding TYRE!

Thats all im saying on the matter, I wish no further part of this thread.

dnsey · Unread post by **dnsey** » 06 Feb 2006, 22:40

I believe that most of the damage is done by ultra-vioet light.
The Xantia's spare is well protected from that at least, so should fare much better than an exposed tyre such as that on a caravan wheel.

Mandrake · Unread post by **Mandrake** » 06 Feb 2006, 23:31

Xantia suspension strut top rubbers are also protected from direct exposure to light, but the ones on mine where stuffed by the time I got it at 8 years old

Humidity perhaps ?

Regards,
Simon

James.UK · Unread post by **James.UK** » 07 Feb 2006, 02:34

Steve. You are obviously concerned about using the tyre. So buy a new one, it's a small price to pay for peace of mind.

With cars, I think a general policy of, "if in doubt, replace it".. is a good one to follow.

Unread post by **RichardW** » 07 Feb 2006, 07:52

Odd isn't it? Ask the question "should I buy a second hand tyre" and a deluge of emphatics NOs follows, based on not knowing the hisory etc. Yet, how many of us would go out and buy a new set of tyres on a second hand car - which amount to the same thing as part worn tyres

I strongly suspect the answer is a large round number....

It's UV that attacks the tyres and cracks them. There's none of this under the car. I'd run the tyre, but note that it's probably a different size the rest on the car, and therefore technically illegal (and an MOT fail) to run it long term. Note also that the support cage may have dented the sidewalls of the tyre and this may lead to premature failure, so keep a good eye on its shape. I'd rather run a half decent Michelin than some real cheapo tyre with suspect levels of grip in the wet.... I suspect failure of the front strut mounts is more to do with water getting in between the rubber and steel and rotting the steel out, rather than failure of the rubber itself.

Mandrake · Unread post by **Mandrake** » 07 Feb 2006, 08:20

RichardW wrote:I suspect failure of the front strut mounts is more to do with water getting in between the rubber and steel and rotting the steel out, rather than failure of the rubber itself.

Not wanting to deviate too far off the topic of this thread, but there are two modes of strut failure - The invisible rusting of the plate caused by trapped water you describe is what happens in the UK.

In some other countries including NZ the plates don't rust but the rubber blocks crack and shear and eventually give way.

The rubber blocks on mine at a mere 8 years old were already so distorted that the round ring that the gaters are supposed to attach to were nearly square.

There was obvious cracking and shearing of the rubber, and I suspect that catastrophic bonnet-puncturing failure of one of them was less than a year away when they were replaced...

Whats the difference in our weather compared to the UK ? Higher temperature and much higher humidity. (Also due to a lack of road salt the plate doesn't get a chance to rust before the rubber fails - rusty Xantia's are unheard of here)

Regards,
Simon

Clogzz · Unread post by **Clogzz** » 07 Feb 2006, 10:28

My spare tyre still has the original 130km/h paper sticker on it.
I use it whenever I have a flat, which is very rare.
It's the fabric inside the case that makes the structure of the tyre.
For as long as the outside looks normal, I will keep it.
Tyres don't deteriorate as fast as they used to, because there's less rubber, and more synthetic in them than before.
Years ago, you saw parked cars with their tyres covered to keep the sun off them in summer.
You never see that anymore.

Kowalski · Unread post by **Kowalski** » 07 Feb 2006, 12:41

Personally, I'd use the spare tyre but common sense says that I'd inspect it first. UV and oil damage the rubber that car tyres are made from, they work on the surface of the tyre and can make a tyre look bad (surface crazing) even when its structurally sound underneath. Rubber is in fact a very long lasting material as long as you don't get it oily or leave it out in the sun. My spare is as old as the car but its in good condition and unused as far as I can tell so I'd have no problem using it.

I have heard of some cars having special "long life" spare tyres, that may just apply to the compact "emergency" type spares where their long life is assured by the fact that you wouldn't use it if you could avoid it

When you've got a spare tyre on you're using a tyre that doesn't match the rest of the rubber on the car, i.e. its not half of a matched pair.

The short version is that I'd recommend you do what you're happy doing. Put a new cheap tyre on the spare wheel if you're happy to do that, otherwise inspect it and if you're not happy about its condition replace it.

Village · Unread post by **Village** » 07 Feb 2006, 13:43

I think the the point of having a spare tyre is that is "spare". If you get a flat, put the spare on so that you can drive to your nearest tyre vendor and have the blown tyre (and perhaps the other tyre on the same axle) replaced, the spare can then go back in its cage/under the boot floor/ under the bonnet(old skool) and you can be back on your way, safe in the knowledge that you have new tyre(s).

I'd rather get rid of my spare tyre, but that means eating less and walking more!

Pete

Sturdybloke · Unread post by **Sturdybloke** » 07 Feb 2006, 19:12

For the sake of £30 inc fitting I would have a new tyre. I value the life of my family to much to risk driving round (even at a moderate to low speed) on a 10 year old tyre - and that includes buying cheapos from the local scrappy (stay well clear). And if you cant afford the £30 for a new tyre then you shouldent have a car at all.

easterroad · Unread post by **easterroad** » 10 Feb 2006, 12:15

was browsing through various websites and found this which appears to be relevant

http://www.carbibles.com/tyre_bible.html

he appears to recommend that tyres older than 6 years are not up to task and that GM and Ford have started to print warnings in their handbooks to this affect from this year onwards

Kowalski · Unread post by **Kowalski** » 10 Feb 2006, 13:10

Tires contain waxes and emollients to protect their outer surfaces from
ozone and weather checking. As the tire rolls and flexes, the waxes and
emollients continually migrate to the surface, replenishing this protection
throughout the normal use of the tire. Consequently, when tires sit
outdoors, unused for long periods of time (a month or more) their surfaces
become dry and susceptible to ozone and weather checking, and
the casing becomes susceptible to flat spotting.

I have heard the old addage that tires last just as long whether you use them or not. Its usually from farmers that I hear it because they tend not to wear their tyres (since they don't always drive on tarmac) and have plant standing around doing nothing a lot of the time (e.g. combine harvesters don't do a whole lot of work during the winter!).