MOT: Cracking around edge of tyres

Alloy wheels and tyre discussion
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Smartbear
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MOT: Cracking around edge of tyres

Post by Smartbear » Fri Jun 07, 2019 6:27 pm

Busterboo wrote:
Fri Jun 07, 2019 9:50 am
Smartbear wrote:
Thu Jun 06, 2019 10:20 pm
Busterboo wrote:
Thu Jun 06, 2019 10:55 am

Most manufacturers' recommended maximum is 6 years, not 16. :rofl:
I don’t think they would fail it for that, the inspection is based on condition not age :thumbsup:
Rob
True, Rob.

For what it's worth, though, my experience of old tyres is that they not only decay at the edges, but also crack between the treads. So, you're driving round on rubber compound that, when it fails, fails 'catastrophically'.

Put another way, who'd want to risk their lives on crappy old tyres anyway?
I remember when poor/mean drivers used to fit remould tyres which were old tyres with a new treaded part glued on, thankfully i don’t think they’re available anymore! :o
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MOT: Cracking around edge of tyres

Post by mmm-five » Fri Jun 07, 2019 7:23 pm

Smartbear wrote:
Fri Jun 07, 2019 6:27 pm
I remember when poor/mean drivers used to fit remould tyres which were old tyres with a new treaded part glued on, thankfully i don’t think they’re available anymore! :o
Definitely still available...Kingpin, Technic, Virager, etc. but you might as well buy mid-range new tyres instead for cars.
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MOT: Cracking around edge of tyres

Post by Thrustyjust » Fri Jun 07, 2019 9:02 pm

Watching Harry's Garage on Youtube and they were talking with Longstone Tyres , as he was getting new rubber for the Countach and they lifed tyres for 6 years , before the rubber dries and you loose traction, grip and general reliability from the tyres. So, I suspect those tyres are beyond their best days , but check the date stamp on them. Also using tyre dressings does protect against UV , so worth considering on some of our cars that dont do huge mileages.
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MOT: Cracking around edge of tyres

Post by Ewazix » Sat Jun 08, 2019 8:20 am

The main causes of tyre cracking are attack by ozone from the atmosphere, lack of use and strain and overheating, particularly from under inflation and UV as mentioned. Tyre compounds contain carbon black (C) which is basically incompletely burnt oil soot. The C molecules are added to stabilise the rubber, transfer heat and reduce rolling resistance and is what makes tyres black. When a tyre is used the molecules in the compound are agitated maintaining the chemical bonds helping to resist cracking. When tyres are not used for a while Ozone attacks the surface of the tyre loosening the molecular bonds in the material, but cracks will not form until the tyre is subjected to stress and strain. So an old tyre that hasn't been used for a while can look fine but will suddenly develop cracks when used again. The cracks develop at the surface where the Ozone has been at work but are not actually a safety issue unless the ply is exposed or the tread is in danger of separating, which is a biggie on our cars and would be the main concern.

I had a perfect example of this when I bought a 14 month old car that had been driven for 300 miles and garaged. The tyres were obviously as new, but within a few months started cracking horribly and had to be changed. This is why buying old tyre stock may be a false economy and I always ask for tyre dates when buying.

In a previous life I helped design parts of the old Sevalco carbon black plant near Bristol which supplied C to many makers around Europe. Different makers are now using various additives and formulations of C to improve performance and some will resist cracking better than others, but there is little you can do to prevent cracking other than using the tyre and keeping it properly inflated. Six years is the industry standard for tyre life although I've had tyres way older than that that have been fine, I've also had tyres with micro surface cracks that never got much worse and were used until worn out.

Interestingly solvents, detergents and other chemicals found in some 'detailing' products may actually degrade the chemical composition of the tyre surface, you would need to check out the exact formulations and do a bit of research but my guess is a lot of them will make tyres look nice but do more harm than good in the long run. I open the floor for informed debate on that one...... :fuelfire:
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MOT: Cracking around edge of tyres

Post by ronk » Fri Jun 14, 2019 7:39 pm

Did you get the car Mot‘d - what was the outcome?
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MOT: Cracking around edge of tyres

Post by ronk » Thu Jun 27, 2019 10:18 pm

ronk wrote:
Fri Jun 14, 2019 7:39 pm
Did you get the car Mot‘d - what was the outcome?
Any news re the MOT ?
You don't stop playing when you get old - You get old when you stop playing!
So I bought a 35is with all the toys to play with. :thumbsup:

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MOT: Cracking around edge of tyres

Post by Ewazix » Thu Jun 27, 2019 10:45 pm

ronk wrote:
Thu Jun 27, 2019 10:18 pm
ronk wrote:
Fri Jun 14, 2019 7:39 pm
Did you get the car Mot‘d - what was the outcome?
Any news re the MOT ?
Looks like it passed with no comments about tyres, so did they get through, or were they changed beforehand?
2003 2.5 SE, low miles, Sterling Grey, 108's & Eagles, no stubby here! Unmolested.
2018 Cooper S Countryman
Fiesta Ecoboost

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