Shelf life of tyres

Horizon81

I know tyres have a shelf life of around 6 years and that the date of manufacture is stamped in the sidewall (e.g. DOT number 3007 means tyre was manufactured in 30th week of 2007).

But when buying new tyres, does anyone ask to check the tyre before buying, to see how old it is? Only asking as it seems that some tyre stockists are happy to keep up to 3 year old tyres in stock and sell them as 'new' tyres, even though they're far from new.

Road_Hog

Horizon81 wrote: »

But when buying new tyres, does anyone ask to check the tyre before buying, to see how old it is? Only asking as it seems that some tyre stockists are happy to keep up to 3 year old tyres in stock and sell them as 'new' tyres, even though they're far from new.

On the same subject, does anyone ever use their spare (permanently) and rotate the new replacement to the boot or does everyone leave the spare in the boot for years?

MX5huggy

The spare is always a just legal 2mm or so left best of the leftovers from when changing a pair.

vikingaero

Horizon81 wrote: »

I know tyres have a shelf life of around 6 years and that the date of manufacture is stamped in the sidewall (e.g. DOT number 3007 means tyre was manufactured in 30th week of 2007).

But when buying new tyres, does anyone ask to check the tyre before buying, to see how old it is? Only asking as it seems that some tyre stockists are happy to keep up to 3 year old tyres in stock and sell them as 'new' tyres, even though they're far from new.

I don't think there's a major problem if the tyre is stored on racking out of sunlight. Once it's on a car in the wind/rain/cold/heat/sun then 5 years is the recommended limit.

mikey72

If it's a good spare, I always use it with a new tyre of the same type, and put it on.
I keep the best of the worst as the spare after that. If I change a better set (usually do them in 2's or 4's), I swap the spare again.

mikey72

vikingaero wrote: »

I don't think there's a major problem if the tyre is stored on racking out of sunlight. Once it's on a car in the wind/rain/cold/heat/sun then 5 years is the recommended limit.

The plasticiers are supposed to "settle" after about 5 years if you don't use them.

Strider590

mikey72 wrote: »

The plasticiers are supposed to "settle" after about 5 years if you don't use them.

Correct.... And here's the more scientific explanation to back this up (for anyone bored enough to read it).

DBP or Dibutyl phthalate, is the plasticiser most commonly used in tyre's.

Dibutyl phthalate's don't bond with the rubber on a molecular level, they sit between the rubber molecules preventing them from bonding (and therefore hardening) together.

As far as I know, it (Dibutyl phthalate) "sweats" out of the rubber over a long period of time, whether the tyre is being used or not. The result is minor cracking along the side wall of your tyre's, which eventually leads to MOT failure.

Ever noticed how elastic bands harden? same thing....

5 years sounds about correct for tyre's, some European countries state a life of 2 years, this is where a lot of part worn tyre's come from..... Some of our new tyre's are in fact old scrapped European stock.

Horizon81

My spare is a space saver so it just sits in the boot.

I just think people should be aware that when you buy a new tyre you should inspect it to see when it was made. I'll be trying this shortly as I need a couple of tyres. I suspect the tyre fitter will see me as some sort of smart alec!

Road_Hog

Horizon81 wrote: »

My spare is a space saver so it just sits in the boot.

Uggh, why do car companies do this, it saves pennies and is nothing to do with space. A car company (a quality one at that) I worked at, decided for a while that they wouldn't even put a space saver in. The first we knew about it was when my colleague picked up her replacement company car and asked me where the spare tyre was. When I stopped laughing, I pointed out that the pot of glue looking stuff and the electric pump (tyre sealant) was her replacement tyre.

I called up the fleet manager and asked what were we supposed to do if the tyre shredded, he didn't have much on an answer. Neither did he like it when I said I wouldn't be putting in my car change until it was sorted, which didn't impress him either, as we used to change at 8,000 which was less than 3 months usuage.

Anyway, spare tyres were soon reinstated.

Mark_Hewitt

Same with my car, pot of foam and a pump. Didn't do me much good when a rock ripped through the side wall.

Strider590

Road_Hog wrote: »

Uggh, why do car companies do this, it saves pennies and is nothing to do with space. A car company (a quality one at that) I worked at, decided for a while that they wouldn't even put a space saver in.

It also saves weight, which is beneficial to wrangling better MPGand power figures.

If I recall, BMW don't fit a spare in the 1 Series (lol car).
The reasoning is that most people now wouldn't change a flat tyre themselves anyway (not just women either) and using the re-inflation kits reflects this change in driver attitude.

I mean ask yourself seriously, would you change your wheel over if you had a flat or would you call your "roadside assistance specialist".