Are your tyres safe?

Eric318

Food for thought...

http://abcnews.go.com/Video/playerIndex?id=4826897

Max_Damage

Jesus, I used to buy my tyres from the scrapyard! Not anymore!

Esel

I definitely will be checking those cryptic date-of-manufacture codes from now on!

Max_Damage

This piece from Wikipedia may prove useful:

The DOT Code is an alphanumeric character sequence molded into the sidewall of the tire for purposes of tire identification. The DOT Code is mandated by the US Department of Transportation. The DOT Code is useful in identifying tires in a product recall.

The DOT Code begins with the letters "DOT" followed by a two numbers or letters plant code that identifies where it was manufactured. The last four numbers represent the week and year the tire was built. A three-digit code was used for tires manufactured before the year 2000. For example, 178 means it was manufactured in the 17th week of 8th year of the decade. In this case it means 1988. For tires manufactured in the 1990s, the same code holds true, but there is a little triangle (Δ) after the DOT code. Thus, a tire manufactured in the 17th week of 1998 would have the code 178Δ. After 2000, the code was switched to a 4-digit code. Same rules apply, so for example, 3003 means the tire was manufactured in the 30th week of 2003.

Other numbers are marketing codes used at the manufacturer's discretion.

I checked the dates on my tyres, and they were made in 1999. Should get them replaced soon enough then.

quickrack

Makes for interesting viewing that!!!

macplaxton

Mine are from a summer 2007 batch, so they are very fresh.

Courtesy of FBHVC (Federation of British Historic Vehicle Clubs):

Newsletter 04-07:

TYRES - WARNING!
Her Majesty’s Coroner for Manchester wrote to FBHVC just after the last newsletter went to press and many will have seen this topic on our website - it is an important matter and we urge clubs to pass the warning on to their membership if they have not already done so.

The letter concerned an accident that took place last year in which the driver of an H registered MG B lost his life when a rear tyre burst on the M56. The driver was a skilled mechanic and a careful and experienced driver who was not travelling particularly fast at the time. The car was described by police as being maintained in excellent condition. The surviving passenger said that just before the accident the driver had commented that a ‘tyre wobble’ had developed and he was going to ‘drive through it’. The wobble went briefly, but then the tyre burst, causing the car to spin, clip a kerb and flip over.

Subsequent investigation showed that although hardly used the tyre was 25 years old. It was one of a set of as-new tyres and wheels bought at an autojumble the previous year for use for showpurposes (at the time of the incident the car was
on its way to an event at Oulton Park).

This note appeared in the Newsletter for December 2003 following a suggestion that tyre dating may become a feature of the MoT: …the Vehicle Standards and Engineering Division at the Department for Transport [has advised us] that although most tyres already carry dates of manufacture in their side-walls, there are no plans to implement regulations to check such dates at the annual MoT test. DfT would, of course, change their mind if tyre failure due to age became a significant cause of accidents.

The British Rubber Manufacturers Association suggests that if a tyre is six years old and remains unused it should not be put into service. It also suggests that in ideal conditions tyres may have a life expectancy of 10 years.

The moral of the story is not to wait for legislation, but to make sure your own tyres are in good condition, never to use undated or obviously old second hand tyres however good the tread and never to ignore a ‘tyre wobble’.

Newsletter 05-07:

MORE ON TYRES
We had two pieces of feedback following our warning about the risks associated with older tyres in the last issue. That warning had been triggered by the death of the driver of an MGB that had overturned following a blow-out.

First, the Tame Valley Vintage and Classic Car Club, of which the unfortunate MGB driver was a member, wrote to say that the deceased had been a tireless worker for the Children’s Adventure Farm which provides free holidays for under privileged and special needs children. This year the club’s 2007 annual ‘A6’ charity run was in support of, and ended at, the adventure farm where a bench commemorating the driver’s life was unveiled.

Second, a reader gently took us to task for not explaining how we were certain that it was the age of the tyre that had caused the catastrophe, and not some other cause, such as picking up a piece of debris or overheating due to underinflation that might have caused a new tyre to fail in the same way. The quick answer is because that’s what the official reports said and it matched with experience - but the point was well made so we looked a little further.

A large section of tread had parted company from the tyre. The police recovered this missing section of tread and matched it to the remains of the tyre. It was found in the verge some eight metres before the first indication of any tyre scuff marks on the carriageway. The report did not specifically state there was no evidence of contact with debris and there was no way of knowing what the pressure in the tyre was prior to the accident, but it was noted that the pressures in the remaining three tyres were above manufacturer’s recommendation. The effects of the burst tyre might have been exacerbated by the fact that the wheel spinner on this wheel was not fully tightened.

Car tyres are made from a synthetic styrenebutadiene rubber which is easy to manufacture and has a significantly lower cost than natural rubber, but it does have the disadvantage that it is more prone to oxidisation. To counter this, tyre compounds contain anti-aging additives as well as ‘extender oils’ that improve grip and elasticity. Unfortunately, the chemicals that provide these properties are themselves harmful to human health and the amounts that may be used are strictly controlled at a level that provides a compromise between the need for the tyres to last a reasonable time and the requirement to minimise the health risk. The ‘reasonable time’ is around ten years, which in the context of tyres for vehicles that are in regular use is more than adequate. The oxidisation means that the character of the compound is deteriorating from day one, but the effect is barely perceptible in the first few years if the tyre is looked after or stored properly.

If a tyre has been in regular use beyond that period there should not be a problem provided the tyre is kept at the correct pressure (to avoid risk of over heating). But if the tyre has been standing for months on end, the oxidisation of the compound means a stiffening of the tyre walls so that when it is next used the unaccustomed flexing will cause heat to build up more rapidly than it would in a newer tyre or one that was used regularly. When the tyre warms to a critical level, the natural degradation of the compound increases rapidly causing the long molecular chains that give the compound its flexible properties to shorten, and ultimately causing the tyre to start to break up. The tyre failure on the MGB was consistent with that picture.

carchaeologist

Max_Damage wrote: »

Jesus, I used to buy my tyres from the scrapyard! Not anymore!

Me too when i had my mondeo a few years back, used to only get 2000 miles a front tyre as the suspention was so shagged,5eu a tyre i paid most of the time!!:D