Inner Tyre Wall Cracking - MOT Failure

Inner Tyre Wall Cracking - MOT Failure

Author
Discussion

dhutch

8,471 posts

164 months

Thursday 13th May
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A) how old are they tyres, they all have date codes on them.

B) what size are they, presumably low profile on an at, ms titanium diesal is bad enough!

C) can't believe how his hasn't been mentioned yet, but have you been straddling the square type speed bumps?

Daniel

AlphaDelta

Original Poster:

73 posts

12 months

Thursday 13th May
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dhutch said:
A) how old are they tyres, they all have date codes on them.

B) what size are they, presumably low profile on an at, ms titanium diesal is bad enough!

C) can't believe how his hasn't been mentioned yet, but have you been straddling the square type speed bumps?

Daniel
On C yes although there aren't many around here. I have been driving into London recently and they're everywhere.

dhutch

8,471 posts

164 months

Thursday 13th May
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Definitely worth avoiding that with anything with even vaugely low profile tyres. One wheel over, one around the side, change sizes from time to time.

9xxNick

760 posts

181 months

Wednesday 19th May
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dhutch said:
Definitely worth avoiding that with anything with even vaugely low profile tyres. One wheel over, one around the side, change sizes from time to time.
What's the thinking behind this?

dhutch

8,471 posts

164 months

Thursday 20th May
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9xxNick said:
What's the thinking behind this?
You don't destroy the inner tyre wall?

9xxNick

760 posts

181 months

Sunday 23rd May
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Unless you're going over at speed (and it's obviously dependent on the severity of the cushion as well) then the loading on the tyre wall is going to be fairly minimal and far less, I would have thought, than going over a slight corrugation on a motorway at 70mph. I'd be very surprised if straddling them at moderate speeds has any effect on the tyre wall.

If you're hitting them at 20+ that may well be different, but then you'd be subjecting the tyre that's going over the cushion to much greater stresses as well.

If the asymmetry of the forces was a significant problem, we'd see a lot more tyres failing through cornering.

dhutch

8,471 posts

164 months

Monday 24th May
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9xxNick said:
Unless you're going over at speed ...

If you're hitting them at 20+ that may well be different, but then you'd be subjecting the tyre that's going over the cushion to much greater stresses...
Given most are in 30 limits, I would expect it's is status normal to be going over at 20+ mph infact 35 is likely common.

If you watch while following a modern car over these humps, attempting to stradde them, often more than half the tyre width comes fully off the ground, focusing a huge force in the inner half of the tyre and inner sidewall. It's a reasonably well known failure mode for low profile tyres.

Daniel

Pastie Bloater

694 posts

130 months

Monday 24th May
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Monkeylegend said:
According to that video storing tyres near to electric motors makes them more susceptible to cracking. Herald a new era of cracked tyres as we move over to electric cars smile
Yep ozone degradation of elastomerics is an issue in industry, coming soon to an EV near you hehe

Smint

95 posts

2 months

Monday 24th May
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I had a similar shock shortly after buying a Landcruiser several years ago, tyres still around 9mm (All Terrain) and looked great, until i was underneath doing some routine service work and noticed a black line all the way around one tyre just above the bead which proved to be a crack about 1mm wide but nearly down to the cords, inspecting the rest proved all were the same yet not a sign of cracking the outside or in the treads, tyres not old by any means and large 70% aspect to straddling road cushions wouldn't be the cause, i'd inspected the motor well i thought pre purchase but hadn't spotted this.

Did my offroader mate some good though, he ripped the cracking set up playing in the mud and rocks.

Isn't an emergency purchase both expensive and annoying, don't know why they do this, once you find out you've had you pants pulled down that's the last time they'll ever see you, if they looked after you (as the garage we use in the centre of our town does, nothing too much trouble) when you needed them you'll become a loyal customer and tell others about them, stupid short sighted business practice to take advantage in the heat of the moment.

InitialDave

8,681 posts

86 months

Monday 24th May
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AlphaDelta said:
New fronts have now been fitted. Nexen tyres. I've no idea if these are any good but I wasn't going to drive away on what I had on there so went with it. At £90/tyre I'd hope they aren't complete ste but I will replace them if they are.
They're average at best, and not worth anywhere near £90 apiece, but ah well, you've got them now, see how you get on.

AlphaDelta

Original Poster:

73 posts

12 months

Sunday 30th May
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AlphaDelta said:
A side issue was pitting on the rear discs. This was an advisory as there's still plenty of disc and pad left. I'm going to take them off and have a proper inspection at the weekend so any advice on this issue and at what point I should be looking to replace the discs would also be appreciated.
I took advantage of a nice bank holiday Saturday in the sun and fitted new rear discs & pads. The rear caliper slider pins were immobile and after some work and lubrication I got the pins out. There was alot of rust so the entire caliper was cleaned, re-greased and put back together with the new discs/pads. I suspect the state of the slider pins was part of why the pads were not making full contact with the disc. One to remember for next time.

Smint said:
Isn't an emergency purchase both expensive and annoying, don't know why they do this, once you find out you've had you pants pulled down that's the last time they'll ever see you, if they looked after you (as the garage we use in the centre of our town does, nothing too much trouble) when you needed them you'll become a loyal customer and tell others about them, stupid short sighted business practice to take advantage in the heat of the moment.
It does drive me nuts. I won't be back to that dealership for a MOT/service again any time soon.