Yokohama A-032R WARNING !!!!
Turbo Mini Forums

Hmm,

yes, as they are not bundled it suggests this is the issue, perhaps the wires were kinked during manufacutre, weakening them at this point.

Would over inflation have caused a different type of damage to the tyre than pictured? It looks like the bead failed at the splice. It may be sods law but may be unluckily the portion of the bead with the splice was the last point around the rim to settle against the flange, got distorted and popped.

Schrödinger's cat - so which one am I ???

as you say i'd never thought about how they are made either,

I had a google but theres nothing particularly informative on the wire,

I would have expected that one peice of wire was used, and and wraped round reveral times, then joined only once, but thats just supposition.

I''' ( think we all will) be interested to hear the verdict from MS

Its not made up of lots of individual wires though, its 1 long piece wrapped round lots of times

I seriously doubt it!

One wire or multiple wires at least one splice vulnerable to distortion and snapping then the other wire loops break in succession as the load transfers. It's like Russian roulette with a very rare factor of getting the bullet but the bullet is there nonetheless.

Edit: What I'm trying to say again is that if the spliced wire was in the last part of the bead to settle while being inflated that could load the splice with enough tension to snap the splice then snap the other wires and break the bead.

Edited by Lot on 4th Oct, 2009.

It must have been stretched a long way and that would only come from the fitters error

Paul

I seriously doubt it!

Just thinking out loud, but if it was overpressurisation, the sidewall looks much thinner and weaker at the "top" (the other end of the tear).

I take Lot's point about any splice(s) being vulnerable to distortion, but the individual wires are very thin so should cope with plenty of bending without failing.

Anyway - speculation - if Gavin hasn't logged on and seen my PM by tommorow morning I'll contact MiniSpares direct.

Schrödinger's cat - so which one am I ???

i used to fit tyres and i have never seen this before, even on buget and remould tyres!

Just a quick update,

Gavin has arranged for it to be collected tommorow to be looked at by Yokohama ASAP.

So, a good response from MiniSpares.

Schrödinger's cat - so which one am I ???

Well, It's been well over a month since MiniSpares picked it up.

I have been in touch with Gavin every week since and still no response from Yokohama despite Gavin's promises.

I have now instructed Gavin to return the failed tyre to me by the end of next week so I can get it analysed by an independant Test House - I have access to a few from my previous work.....

The fact that MiniSpares and Yokahama have done nothing in over a month makes the need for an independant evaluation fairly obvious...

Schrödinger's cat - so which one am I ???

I think I might have wanted to bypass the retailer and gone straight to the manufacture. I did the same about 3 months ago and some Dunlop's on my Daily Drive. The retailer didn't want to know.. however a letter the the MD and I had them switched inside a week.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

hell, they look quite thin in places to. prob normal for tyres i'm guessing though.

Best 1/4 mile 13.2 seconds @116 mph
First 5 port miniturbo to make over 200 bhp on a carb?
First 5 port miniturbo to make over 200 bhp on Injection?

http://www.mattwoodsphotography.com

Schrödinger's cat - so which one am I ???

Well I've had this back from Gavin

"Yokohama have said that the failure was due to fitment"

The tyre is on its way back to me and I've asked Gavin for a written report from Yokohama so I can pass it on to VOSA.

In my opinion there is no way the bead wires could have failed because of any errors in fitting it. I've done a few basic calculations and if the bead wire was the specified stuff it would have a UTS of 1800MPa. There is no way that would fail at 45psi. Even if the company who fitted it were lying about the pressure they used, my calculations (counting 20 strands of 0.9mm) say it would need at least 150psi to fail that bead wire.

So, once I have the tyre back, I will leave it to VOSA to decide but, in the meantime, my project goes nowhere.

My life is worth more than the cost of four tyres.

Edited by Rod S on 18th Nov, 2009.

Schrödinger's cat - so which one am I ???

Rod the issue I had with the Dunlops above were two fold, but the fitter had damaged the bead when putting them on the rims. There wasn't any lube used and they had cut the tyre in several places. There was also damage to the side-wall. You had to steer the wheel 15deg to the left to go in a straight line. The issue I had was everyone saying this was a tracking issue however, I now know of three other people with similar damage that caused the steering issue. ( I had the same issue with my wifes car and the same fitter, it only came to light once I had sorted this out)

I was very lucky Dunlop swapped the tyres out, however this had nothing to do with good will or fitting... They had been made in AUS and therefore shouldn't have been in the UK and they wanted to trace the source. They were extremely worried I believe as the compound would have been very un-usable in our weather.

When I first saw yours I did think the same as Yokohama stated above.

Edited by gr4h4m on 18th Nov, 2009.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

UPDATE....

The written report from Yokohama was worthless



Gavin has seen this and agrees it was not the detail either of us was expecting but in the meantime I got myself a contact at VOSA.

They were very slow at first but burst into life today after a "reminder".

Whilst waiting for VOSA to get into action I also emailed Yokohama pointing out their letter was worthless and demanding a proper report.

Their letter is factually wrong, the tyre was back with me (via Gavin) before they even wrote it saying the tyre was in their warehouse.....

Anyway, after getting hold of the right person in VOSA (Head of Vehicle Safety according to his eMail signature), VOSA have agreed to examine the tyre themselves !!!!

They have given me the neccessary form to fill in and will even collect the tyre from me by courier.

I have said wait until the "one calender month" Yokohama said in their letter about disposing of a tyre they don't actually have..... before I arrange it's collection by VOSA and they agree.

So if I don't get a suitable response from Yokohama direct, VOSA will have a nice Christmas present.

Schrödinger's cat - so which one am I ???

I cant understand this...

IMO form the pic the wires are not bundled corectly in the tyre, the only way this can happen is when the tyre is made :?

Joe, I agree - they do not look bundled correctly.

I have researched this a lot and the individual wires should have a VERY thin layer of rubber before being bundled to mechanically and electrically insulate the individual strands, but they should still be in a tight bundle. The cup/cone failures are also wrong IMO as they seem too large for the wire diameter.

Minimum UTS of bead wire should be 1800MPa (ie, very strong) and with 20 wires on view and the measured diameter, the required load to fail it is immense.

Anyway, enough speculation.... once Yokohama have had their "one calender month", it's off to VOSA

Schrödinger's cat - so which one am I ???

Yoko aren't trying to hide behind "no defects *subject to our warranty cover* have been found" are they? Worth checking exactly what the Yoko warranty covers?

Stilll, you'd hope for a more quantitative response than the airy fairy stuff given. See what VOSA have to say next...

is damage by the fitter totally out of the question?
depending on how easily the tyre bead seats on the rim then imo 150psi isnt out of the question surely. some wheels ive come across take a lot of psi to seat the bead, and a lot of tyre guages ive seen dont give the psi reading whilst inflating tyres if im not mistaken, so how could the fitter know it was 45 psi? just a thought.

personally i dont think you will ever get to the bottom of it, yoko will never ever admit to it being faulty manufacture, the tyre fitter will never except he did it coz it will cost him 45 quid for a new tyre and not sure if vosa will be to bothered tbh as it hasnt failed whist being used on a car.

no longer a series, but still 1.3 turbo.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Schrödinger's cat - so which one am I ???

I have always had the feeling that it was a fitting problem. Although the pressure may have been limited to 100/120psi I dont feel that the possibility of higher pressure alone was the problem.

With a modern tyre fitting rig it is easy to force a tyre on to a rim even if it has not been properly postioned/lubricated and even fit it from the "wrong" side if that was applicable.I have seen inexperienced tyre fitters applying what I considered far too much force to get a bead over the rim when all it needed was to "jiggle" the tyre a bit and it would slip on.

The bead could have been ruptured like this and a bit of overpressure would do the rest.

Only theory based on other observations, but ,as I see it, the only alternative is that it is a tyre that should never have passed inspection.

As Carl says its unlikely anyone will admit anything, but all credit to you for trying.

Will you go back to the same place for any other tyres - or fitting ?

All valid points.....

The reasons I'm persuing it is that, if it is a manufacturing fault, others could be at risk (although it could equally be a one-off fault and me being the unlucky one).

Taking those points though, it wasn't a modern tyre fitting rig designed for all those chav/pimp 20" wheels !!! The place I used is one of only two in the area who still have a machine that will do 10" wheels. It is very basic and, although I wasn't there to watch this time, I have watched - usually chatting to the manager/owner as he does it - and never seen a problem with my son's Mini (12" wheels) or anything any bigger.

And there is absolutely no indication of it having been forced onto the wheel, no cuts, nicks, abrasion or distortion of the bead (I have the tyre back here now and have looked at it thoroughly again) and it was not forced on.... the only damage is the failure, a straight tear up through the bead and sidewall, nothing anywhere else, and the start of the tear is absolutely clean.

And the Mambas don't need any significant force to snap the beads in place - they don't have the "safety" lip that modern wheels do.

I took the old tyres off the wheels myself (in order to clean up any corrosion etc.) with no problems at all, easier in fact than taking a tyre of my Lawn Tractor (a regular occurence with hawthorn hedges around the garden) which is a 12" wheel at the back, because those wheels have the safety lip.

And beads shouldn't "rupture", they are supposed to be a close packed bundle of extremely high tensile steel wires (1800 MPa minimum) with only a thin layer of rubber seperating the individual strands so each strand should carry an equal load.

As for it passing inspection, what inspection ??? I doubt there is anything worthwhile on an automated process, just checks on the parameters that control the automation.

About 5 years ago I took wifey's previous car into the same place for two new well known brand tyres supplied by the same place (rather than bought from someone like MiniSpares and just taken in for fitting). Both went on fine but when the second one went on the balancing machine it showed as needing 180g on both rims... He said it must be a buckled wheel, I said no as the weights were in roughly the same place, not opposite angles, he tried again, same result, so I said take the tyre off and try the wheel by itself... wheel was fine so we looked inside the tyre and at one location there was a totally visible extra layer of nylon/rayon "plies", obviously the beginning or end of the wrap and the wrapping machine had obviously screwed up. That tyre should not have passed the most basic of visual examinations, let alone any proper sub-surface examination.

So, I will persue it until I fail........

And yes, I will go back unless or until, I have proper proof it was his fault.

But in the meantime I will fit a couple myself next week (just waiting for a new tub of bead lubricant to arrive as I used the last on my lawn tractor a while ago) to see if there is anything about the Mambas that I've never noticed before when having them fitted elsewhere.

Unfortunately, although I can fit a tyre no problem, I don't have a balancing machine.... not a problem on the lawn tractor but probably a problem on the Mini !!!!

(next project, home made on-car balancing rig.....)

Schrödinger's cat - so which one am I ???