Why am I blowing up inner tubes?

[Kermit power]

My wife's bike has the tyres it originally came with. I'm fitting the right size of tube. I've religiously gone round the tyre and the rim tape to make sure there's nothing in there that could be causing a puncture.

The last two tubes I've put in the rear exploded on me at around 90 PSI, in a tyre rated at 80-100 PSI. So long as I don't take the pressure over 80 PSI, there's no problem.

Any idea on what might be causing the issue?

[Rouleur]

Bit of a head scratcher this one, but maybe try rubbing some chalk dust around the tyre..? The tube must be pinching somehow so I reckon you need to reduce any friction in there.

[Kermit power]

The weird thing is that it works fine at lower pressures.

The tyres are getting on a bit - might that have an impact? Can they stretch, causing the tube to over-expand or anything?

[Mr Gear]

Is the tyre pinching the tube against the rim?

1) Install inner tube and seat tyre
2) Pull the tyre side to side all around the rim
3) Inflate tyre to 20 psi
4) Repeat #2
5) Inflate to full pressure

Any good?

[Mars]

Christ..!! How are your ears? After a tyre popped off the rim at ~60psi whilst I was pumping it up recently, it took severaly days before my right ear went back to normal. I *was* in the garage, so the effect was compounded. I now have a (very) small inking what it must be like to have a grenade go off nearby.

[Ken Sington]

This happened to me a while back and it was down to an absolutely minute piece of flint that was embedded in the tyre. Almost too small to see/feel but big enough when the tube was under pressure to cause punctures, so check very carefully.

[Kermit power]

Mars said:

Christ..!! How are your ears? After a tyre popped off the rim at ~60psi whilst I was pumping it up recently, it took severaly days before my right ear went back to normal. I *was* in the garage, so the effect was compounded. I now have a (very) small inking what it must be like to have a grenade go off nearby.

Was it you that started a thread on that? If so then thanks, as I decided as a result of reading it to pump tyres outside in future!

[Mars]

Kermit power said:

Mars said:

Christ..!! How are your ears? After a tyre popped off the rim at ~60psi whilst I was pumping it up recently, it took severaly days before my right ear went back to normal. I *was* in the garage, so the effect was compounded. I now have a (very) small inking what it must be like to have a grenade go off nearby.

Was it you that started a thread on that? If so then thanks, as I decided as a result of reading it to pump tyres outside in future!

Ha, yes. That was me. I do same now (outside only).

[Rocksteadyeddie]

LIkely to be a tiny little piece of something in the tyre. If they're past their best junk them and replace. Experience has taught me time and again that early tyre changes pay you back.

[yellowjack]

Rocksteadyeddie said:

Experience has taught me time and again that early tyre changes pay you back.

I would strongly agree with that. The wife, who doesn't drive (her choice), depends on her bike to get to work. She is also 'allergic' to maintenance, and when questioned about the state of her stead would always reply "it's fine". Up until the point where it was fitted with new tyres because she was puncturing at a predictable rate due to a complete lack of tread depth and many tiny particles of road debris embedded in her tyres. There were so many cuts and perforations in them it was a wonder that she ever got to complete a return journey without a flat. Worst of all, I found out that she'd been paying Hellfrauds to repair/replace inner tubes because there's a branch on the way home and it's the only place open after she finishes work - never once was she advised to replace the tyres as well as the tubes, nor was she advised (by so called industry professionals) that a hell of a lot more work was required to keep her on the road. Off topic, I know, but a chain, cassette, rear mech, full cables, and new pedals later, I had her back on the road and she said "it feels brand new". As an aside, before binning the old tyres, I dug around in one of them with a mini screwdriver, and the volume of flint/swarf/glass/grit that came out of all the cuts and holes was truly surprising. It was no wonder that some of it worked it's way through to hole the tube over time.

[anonymous-user]

May be a stupid question, are you sure the gauge is accurate? 100psi on the gauge may be far higher in reality!

[Kermit power]

Jimboka said:

May be a stupid question, are you sure the gauge is accurate? 100psi on the gauge may be far higher in reality!

I've not got any real way of measuring this, but I've not had any problems with my road bike, my mountain bike, any of the kids' bikes or the other wheel on my wife's bike, so I think it's safe to assume it's specific to this wheel!

I'm going to get a new tyre for it and see if that sorts the problem.

[ndg]

It could just be bad yubes? I had a couple of cheao tubes from CRC that kept exploding when I tried to pump them beyonf 80psi. Switching to a different brand solved the problem. Not all tubes are equal!

[anonymous-user]

Kermit power said:

I've not got any real way of measuring this, but I've not had any problems with my road bike, my mountain bike, any of the kids' bikes or the other wheel on my wife's bike, so I think it's safe to assume it's specific to this wheel!

I'm going to get a new tyre for it and see if that sorts the problem.

So you could be well over inflating the tires in the first instance?

That said my PSI reading on my track pump is about 15% over so at a 120psi it's near on 140psi, I know this because I also have a more accurate hand held psi gauge. Pump gauges are notoriously in-accurate so you may just be putting too much air into your tubes, however in my experience way too much PSI and the the tires comes off the rims or bulges at a weak point in these circumstances too. So it maybe something on your rim rather than in your tire.

Edited by anonymous-user on Monday 13th June 10:50

[mattviatura]

This happened to me. I'd done under 5 miles on my new bike when it got a puncture. I changed the tube and next time out got another puncture in the exact same place.

There was nothing in the tyre and the wheel was fine - it was a new bike.

I called the shop (feeling very foolish) and took the bike in, they fitted a tube and overinflated it. It punctured in the same spot.

The rim tape had a sharp edge and the inflated tube exposed it. They changed the rim tape and it's been fine.

[JPJ]

It might be a very small split in the tyre - only when it's fully inflated does it create a big enough hole to pinch the tube and then when you roll the bike on it it causes the puncture.