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Exploding inner tubes

Old 03-18-19, 04:11 PM
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JKjks
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Exploding inner tubes

I have been setting up my older childís old bike for the younger one to use. The first time I pumped up the rear tire, the inner tube exploded. It looked like the tire had deformed because it had been standing unused for so long with a flat tire, so I bought new tires. Just installed it with a new tube and the inner tube blew out again.

can anyone suggest why this is happening? It is a 24inch wheel, the tire is rated to 60-80 psi and I was inflating to 70 using a floor pump with a pressure gauge.
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Old 03-18-19, 04:19 PM
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Is this a BMX/MTB (fat tires) or a Road Bike (skinny tires)

For BMX/MTB, you're probably better off with < 50 PSI.
For Road (1" or 25mm or so tires), then your pressure would be about right.

Try inflating the tire to about 20 PSI, then remove the pump and carefully inspect that the bead is even all the way around the tire.

If not even, deflate and adjust, or look for an entrapped tube.

If all looks good, then bring it up to full pressure.
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Old 03-18-19, 04:31 PM
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Adding to CliffordK's excellent advice, check the inner side of the rim walls---if there's nothing like a ledge there (called a "hook" by rim manufacturers), that means that it's a "straight-sided" rim and that the pressure range rating of the tire doesn't apply.

Also, if the younger child weighs less than 100 pounds or so and if the tire is as wide as or wider than a standard 20" BMX bike tire, the maximum pressure range is irrelevant and the appropriate pressure is more likely to be 40 or 50 psi or even less.
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Old 03-18-19, 05:05 PM
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So Iím basically over-inflating the tube? Thank you. Iíll try with a lower pressure and make sure the tire is seated correctly. My son is definitely under 100lb.
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Old 03-18-19, 05:09 PM
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I'd also check the rim tape and make sure it's fully covering the nipple head or the hole in the rim (depending on rim style). A tube exploding means the tube is freely able to expand somewhere. I do as Clifford suggests. I fill my tires to 20psi first and then check the tire, normally bouncing it around to seat things. I then bring it up to pressure.

Originally Posted by JKjks View Post
So I’m basically over-inflating the tube? Thank you. I’ll try with a lower pressure and make sure the tire is seated correctly. My son is definitely under 100lb.
No you are inflating it as you should. The tire it rated for more pressure than you are using. Something else is the cause of the problem. Check the tape first, then check that the tire seats properly as you inflate the tire.
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Old 03-18-19, 07:11 PM
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I had this happen to me once...tube got pinched between the tire and rim......I learned tire changing the hard way.

Had it mounted up ready to roll and walked away. 30 minutes later it blew! Loud and scared the crap out of me.
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Old 03-18-19, 08:43 PM
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Originally Posted by sdmc530 View Post
I had this happen to me once...tube got pinched between the tire and rim......I learned tire changing the hard way.

Had it mounted up ready to roll and walked away. 30 minutes later it blew! Loud and scared the crap out of me.
That's what I suspect is happening too. It's easy, if you are not careful to trap a bit of inner tub e under the tire bead. When that happens, the air pressure in the inner tube can eventually lift the tire bead off the rim. Sometimes it happens immediately, sometimes it waits and takes you by surprise later. It's worth the time that it takes to check both tire beads, all the way around to make sure that hasn't happened.
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Old 03-18-19, 09:01 PM
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In addition to the good advice given above, some tires run a bit loose, and it's possible that the bead doesn't properly seat itself as the tire is inflated. On new tires, I pump them up slowly, adding a few PSI, then checking all the way around to make sure it looks like the tire is meeting the rim uniformly all the way around. Then I pump it further and look again. If the bead isn't seating, you can deflate and try again, or work the tire with your hands until it's uniformly seated.

The studded tires presently on my winter bike needed this kind of attention, though they fit just fine on another bike.
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Old 03-19-19, 09:50 AM
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Yes...

Another issue is: installation errors , one to check each time is, that the tube is between not under the tire bead ,

having it under the bead, it Pushes the tire off the rim , and then the tube unrestrained by the tire casing , pops.

so.. once the tire is on, go around the wheel and double check,

for the lack of any remaining inner tube not where it should be....



NB; some tire beads are out of Spec. made by the many millions errors happen ...




....

Last edited by fietsbob; 03-19-19 at 09:56 AM.
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Old 03-19-19, 10:00 AM
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All good advice although I've found that if I check the tube before inflating and it's not "trapped" between the tire and the rim, it inflates properly. Also, I can't imagine inflating a child's bike to more than 25 - 30 psi which is what I've always done.
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Old 03-19-19, 10:08 AM
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You might want to do as someone else mentioned also and that is check the tape on the inside of the rim and make sure you don't have any spoke ends poking through or a sharp nick on the side of the rim from hitting a curb that is protruding inward. Good luck.
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Old 03-19-19, 10:33 AM
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Originally Posted by 2old View Post
Also, I can't imagine inflating a child's bike to more than 25 - 30 psi which is what I've always done.
I would guess that as 24in wheels, the tires are probably 1.5in or thereabouts.
As an adult who weighs 140 and carries a pannier always, I run my bikes with tires in that size range at about 35-50psi tops, and thats for 35mm 700 tires.
with a kid under 100lbs, 25-30 is completely in the normal range, too high pressures just makes the ride harsh for the kid.
Im trying to remember when my kids were young what pressures I put, but I think I just did a thumb test

might as well ask though, what tire width are they?
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