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NZ, worn inner tube causal in rider death.

Discussion in 'General Motorcycling Discussion' started by robsalvv, Feb 11, 2014.

  1. Thought this best fitted in General - beware all those with old bikes with inner tube tyres... replace the tubes with the tyres.

    = = = =


    Motorcyclists are being warned to heed international laws on changing tyres after a coroner found New Zealand regulations may have contributed to the death of a biker.
    Bryan Wyness, 71, died following a crash on State Highway 1 at Rangiriri, on July 20, 2012.
    The front tyre of his 2004 BMW motorbike had a slow leak, and a sudden deflation caused the tyre walls to collapse, sending Mr Wyness crashing into the central barrier, Coroner Gordon Matenga ruled.
    Mr Wyness drifted into the right lane, in front of a car preparing to overtake him, before smashing into the barrier. He suffered fatal spinal injuries.
    A police investigation found Mr Wyness' tyre tubes were likely the original tubes which came with the bike when he bought it in 2004. The front tyre tube had worn away, causing a small leak.
    This highlighted an "important safety issue" for bikers, Mr Matenga said, pointing to evidence which showed that in Germany, the United States and England it was the law that the tyre tube must be changed at the same time as the tyre itself. Tyre manufacturer Pirelli also has a warning on its products.
    "This does not reflect the law in New Zealand," Mr Matenga said.
    "Motorcycle tyre mechanics are able to reuse the old tube when replacing worn tyres. This is clearly a concern."
    Evidence heard at the inquest was insufficient to call for a law change, he said, but instead called for the issue to be drawn to public attention and raised as a point of concern with the New Zealand Transport Agency (NZTA) and the Accident Compensation Corporation (ACC), as well as motorcycle safety groups.
    "Motorcyclists should at least be made aware of the potential for danger," he said.
    Mr Matenga made three recommendations, requesting a copy of the inquest findings be sent to NZTA and ACC, that bikers are warned that if they do not follow manufacturers advice it could lead to "possible serious injury or death", and that NZTA and ACC should promote a similar safety message on their websites.
    - APNZ
  2. Whilst I agree that worn tubes can be a cause of sudden, possibly catastrophic, tyre deflation (I've experienced it myself more than once), changing the tubes with the tyres being a legal requirement anywhere is news to me. It certainly didn't used to be the case in the UK. I can, however, see it as being a product/supplier liability matter.

    But yes, keep a very close eye on tube condition and type. Indeed, with the current crop of Chinese bikes I'd be inclined to bung decent tubes in from the word go. Tube condition is also very important if you've been a bit naughty and stuffed an oversize tube in as an emergency repair. This can easily result in creases in the tube when inflated, every one of which is a stress raiser/weak spot. I had a front tyre go on my old MZ as a result of this one and it wasn't fun.

    Oh, and I would never ride a tube tyred bike with a slow leak. It's too easy for it to become an explosive leak without further warning.
  3. Interesting. It's not something I'd considered, having never owned a bike with tubed tires and give a push bike will go through several tubes for a single tyre.

    Can someone explain to the genuinely ignorant why a tube tyre flat is so much more catastrophic than a tubeless flat?
  4. Sudden deflation of either is equally catastrophic. However, it is much more likely on a tube type tyre.

    Tubeless tyres have a certain degree of self sealing ability. Get a nail in one and you might not even know it until your next visual inspection. OTOH, if the nail then comes out, the tyre will deflate as quickly as any other.

    Get a nail in a tube tyre and the tyre will go flat in fairly short order. I've noticed that modern tubes seem to be a bit more resilient than they used to be. Once upon a time the result of a puncture tended to be explosive decompression but the last couple I've had on the DR have given me a bit of warning as the tyre's gone down.

    Another factor is the stiffness of the tyre itself. A stiff tyre carcass will hold its shape to some extent, even without air, allowing better control than a flexible tyre which will simply collapse. Trouble is, rigid tyres work like crap when they do have air in them. The OEM Bridgestone Trailwings on the DR are a case in point. Super stif, the bike is (sorta) rideable even with no air in them, but it's still rubbish even when they're at the appropriate pressure :D.
    • Agree Agree x 1
  5. #5 robsalvv, Feb 12, 2014
    Last edited: Feb 12, 2014
    I've had a rapid front tyre deflation - tubeless sports tyre. Thankfully I was vertically upright at the time and I was on a straight.

    The bike becomes effectively unsteerable. The scary part is that momentum and inertia effects makes the bike want to fall over as soon as you make a steering input. Keep the bike vertical and slow down as quickly as is safe.

    A nail in a tubeless tyre will cause a slow deflation which should be manageable as soon as you notice the bike becoming heavier to steer. In my case a rock had been kicked up by an oncoming car and it hit the front tyre's rubber air valve. It near decapitated the valve which was not helped by the valve having been there for a loooooong time and have become partially oxidised and brittle. You SHOULD replace your valve's every second or third tyre.

    I've since moved to aluminium side valves... I should have done that years ago.

  6. On a tubeless tyre, the carcass which retains the air is reinforced by belts, and also by relatively thick rubber.

    On a tubeless tyre, the carcass which retains the air is a simple, non reinforced rubber bladder.

    Tubeless tyre punctures (common scenarios) do not often result in tearing of the carcass, and rapid pressure loss. The reinforcing pies and thickness of the rubber casing often "squeeze" enough to slow the escape of air (sometimes trapping the embedded object and preventing air loss entirely), and also preventing the puncture from enlarging or tearing.

    Tube punctures however, have no reinforcement in the bladder to prevent the puncture from tearing and increasing the speed of pressure loss. While not a wonderful example, think of a balloon - when punctured, the puncture site rapidly expands, tearing in multiple directions and rapidly deflating. An exageration, but none the less...
    • Agree Agree x 1
  7. Tubeless tyres are have a pretty good bead lock onto the rim, whereas Tubeless tyres do not and rely on the infation of the innertube to push the tyre against the rim. When a Tube Tyre goes flat the tyre/carcass can rotate on the rim, so if you are riding and have a lost most of your air then have to use your brakes they can be life threatening as the rims stops and the tyre/carcass keeps rolling around on the rim!