Tyre blowout advice

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silva

Über Member
Location
Belgium
The plus is that you can cut out new sunglasses before binning it.
 

Tom B

Guru
Location
Lancashire
Just my tuppeneth worth but I usually try to install or fit tyres with the start of the branding or similar feature inline with the valve.

That way if I get a puncture I can find it in the inner tube and easily locate the corresponding spot on the tyre to check for sharp objects.

In this case you could check to see if it is the same place on each occasion or moving around.


The only time I've had a failure like that was riding over inflated old tyres. I'd pulled over under a viaduct to explore the curious bumping sensation when the tyre wall split the inner tube popped and left a chap at a bus stop under the bridge diving for cover
 

Once a Wheeler

…always a wheeler
Such things have happened to me. On tour, I would usually carry a 20cm section of outer cover. This can be fitted in under the torn cover and, inner tube repairs permitting, make a good-enough mend to get you to a bike shop. A lumpy ride but it gets around the problem for a few dozen kilometres.
 

Ajax Bay

Guru
Location
East Devon
Such things have happened to me. On tour, I would usually carry a 20cm section of outer cover. This can be fitted in under the torn cover and, inner tube repairs permitting, make a good-enough mend to get you to a bike shop. A lumpy ride but it gets around the problem for a few dozen kilometres.

Well the OP carried a spare tyre: a "good enough" solution, albeit 200g heavier and (more of an issue when touring) extra volume.
 
OP
OP
R

roubaixtuesday

self serving virtue signaller
More woe.

We have been running the randonneur slightly overpressure (85 psi vs 75 nominal rating, religiously checked every morning) and all seemed fine until another failure this morning, about 400 miles use only.

The bead has failed *inside* the casing which rubbed a puncture, happily, rather than a blowout.

The Conti GP5000 is now on, again just slightly overpressure (110 vs 100 nominal). Our hope is that the extra pressure over the Vittoria will help support the weight. This is also the advice of Swallows, who built the tandem and wheels. They're very surprised we've had these issues.

Intend to get another gp5000 spare, will probably need to order ahead somewhere.

Pic of inside (blue arrow pointing to protruding bead) attached. On the outside there's no damage from the rim, just a tiny split on the surface material. Have also attached a pic of that, though it's hard to see anything.

Thoughts?

1000004919.jpg


1000004911.jpg
 

ExBrit

Über Member
More woe.

We have been running the randonneur slightly overpressure (85 psi vs 75 nominal rating, religiously checked every morning) and all seemed fine until another failure this morning, about 400 miles use only.

The bead has failed *inside* the casing which rubbed a puncture, happily, rather than a blowout.

The Conti GP5000 is now on, again just slightly overpressure (110 vs 100 nominal). Our hope is that the extra pressure over the Vittoria will help support the weight. This is also the advice of Swallows, who built the tandem and wheels. They're very surprised we've had these issues.

Intend to get another gp5000 spare, will probably need to order ahead somewhere.

Pic of inside (blue arrow pointing to protruding bead) attached. On the outside there's no damage from the rim, just a tiny split on the surface material. Have also attached a pic of that, though it's hard to see anything.

Thoughts?

View attachment 731205

View attachment 731206

That's exactly what happened to me during a 600km ride. It's a badly made tire.
 

Dogtrousers

Kilometre nibbler
It's now happened to three tyres...

Have you considered that you might have been cursed?
 
Location
Loch side.
Here's a Parthian shot on the issue. Overinflating a wide 32mm tyre by 10PSI is far more dangerous than overinflating a 23mm by 10PSI.

Overinflated tyres fail by hoop stress, in other words stress accross tye tyre, not along the tyre.

This may help you visualise it. Draw a 1 cm band across your tyre and count the number of of square cms (inches make this awkward for now) in there. Pretend your tyre doesn't have a rim and is a perfectly round tube. You'll count 10 x 1cm squares in that band because 2 Pie R etc.

Now do the same with a 23mm tyre. You'll count only 7 squares in there - three fewer than the wider tyre.

At the same pressure in both tyres, the hoop stress in the 32mm tyre is 42% more.

In other words, a similar increase in pressure creates a disporportionately large increase in stress.


Moral of the story: don't overinflate your tyres, boys and girls. And stay away from whatever crap tyre we're discussing here.
 
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