Tyre deflating

[AlastairS]

Hi I have 37mm Vittoria Voyager Hyper tyres on my bike.
I think I have Vittoria lightweight tubes.
I usually inflate the front to 40 psi and the rear to 60.
But if I inflate the front more to about 45psi, the next morning the tyre is flat!
The front tyre will keep its pressure for days if I inflate to 40.
Do you know what's likely to be causing this ? Thanks, Al

[andrewjoseph]

I think you may have a puncture that the extra pressure is forcing open.

[AlastairS]

Thank you andrew, pretty obvious really, but not for me.

[CJ]

I think you may have a puncture that the extra pressure is forcing open.

Almost certainly.

Could be a displaced rim tape (so a bubble of innertube extrudes into nipple socket and pops) or improperly seated valve (so little bubbles of innertube extrude under it from either side and occasionally burst), or suchlike.

I used not to bother with those valve securing rings, taking my cue from Michelin when (for a while in the '90s) they ceased to provide them - or even any threads on their valves, relying on inflation pressure to snug the valve down into the rim well. But since damaging a couple of tubes in the latter manner, I now use them again - and I note that Michelin valves now have threads again.

[cycleruk]

Take the tube out, but before you do make a note of the tyre to tube orientation.
Make sure you know which way round the tube is so that when you locate the puncture you can find the same spot on the tyre. That way you can check the area on the tyre for whatever caused the puncture.

Pump up the tube and put it in a tub of water (basin bucket or sink) and look for tell tale bubbles. If it is a thorn then the hole may be very fine and will take some finding. Now match up the hole position to the tyre and check for the cause.

[Brucey]

I have experienced the same kind of deflation syndrome with patches that lift, allow the tyre to deflate, then seal again (for a while).

If you have any patch on the inside of the tube, and/or the tube is at all stretched when the tyre is inflated, then patches are apt to lift in this way.

cheers

[AlastairS]

Thanks for help, will try at weekend with water in basin - no patches on tube at moment.

[fatboy]

I'd chuck the tube and start again!

[Vinko]

Yesterday I fitted an brand new inner tube. It stayed up all night, checked pressure again this morning and today I went out for a ride.

Did about eight miles and.....



........"B A N G " ....(was quite a bang too!)

I am glad I have just read this thread though as I was a bit puzzled - so thanks to CJ for his suggestion above.
Now I think about it, it didn't feel right when I fitted the tyre/tube and I so guess (in fact am fairly sure) the valve didn't seat correctly and some of the tube got trapped.

Lesson learnt !

(Fortunately I had a spare tube and pump with me and able to get home!).

[NATURAL ANKLING]

Hi,

Yesterday I fitted an brand new inner tube. It stayed up all night, checked pressure again this morning and today I went out for a ride.
Did about eight miles and.....
........"B A N G " ....(was quite a bang too!)

inner tube.JPG

I am glad I have just read this thread though as I was a bit puzzled - so thanks to CJ for his suggestion above.
Now I think about it, it didn't feel right when I fitted the tyre/tube and I so guess (in fact am fairly sure) the valve didn't seat correctly and some of the tube got trapped.
Lesson learnt !
(Fortunately I had a spare tube and pump with me and able to get home!).

That also looks like some I have had, one after the other on inflation............... ........very small burrs on the largest diameter of the rim, so small I missed them even with my fingers, take a good look.

[reohn2]

I'd chuck the tube and start again!

I never understand this reasoning.
A patched tube is every bit as good as new one,I have some tubes with quite a few patches on them and at the rate I puncture(about twice a year on average)they're quite old tubes,but they still stay up and keep trundling on.
I can count on one hand the number of patches I've had fail or lift and invariably they've been the C cure ones.TipTop patches(the ones with the orange zig zag edges) are,well,err, tip top,if applied correctly.

[beardy]

Yet that particular tube is deflating itself and we dont know why so his reasoning is perfectly sound.

My personal suspicion is that the valve stem is partly separated, this can be tested by holding the tube and wiggling the valve and then you see the gap open, yet it can still hold air when in the correct position.

I have had mystery deflations before, I go through the puncture routine and find nothing, so you return the tube and think "what a mystery". It has happened while I am cycling, ruling out pranksters.
I am not blessed with a good enough memory to recall how those particular tubes got on after that, yet they performed well enough at the time.

I can understand that if you dont want to do additional puncture stops you would just throw away any such suspect tubes.

[mjr]

A patched tube is every bit as good as new one,I have some tubes with quite a few patches on them and at the rate I puncture(about twice a year on average)they're quite old tubes,but they still stay up and keep trundling on.

Indeed. Keep the spare tube in reserve to deal with punctures like Vinko's!

[karlt]

Yesterday I fitted an brand new inner tube. It stayed up all night, checked pressure again this morning and today I went out for a ride.

Did about eight miles and.....



........"B A N G " ....(was quite a bang too!)

inner tube.JPG

I am glad I have just read this thread though as I was a bit puzzled - so thanks to CJ for his suggestion above.
Now I think about it, it didn't feel right when I fitted the tyre/tube and I so guess (in fact am fairly sure) the valve didn't seat correctly and some of the tube got trapped.

Lesson learnt !

(Fortunately I had a spare tube and pump with me and able to get home!).

Looking at that I can virtually guarantee that some of the tube was trapped. I did it once fitting some new tyres; colossal bang as I hit 80psi.

[NATURAL ANKLING]

Hi,
Do you inflate the tube to form the inner tube to shape then place it in the tyre
Splits like that can be trapped tube.
But mystery deflations where even pumping inner tube right up bigger than the tyre and immersion in water with no bubbles mean you have to bin it.