Exploding tubes

I'm totally dumbfounded as I have exploded three different inner tubes on the rear tire for my wife's beach cruiser style bike this summer:

• first time was during initial after-winter prep. Inflated with my regular compressor with regulator set full open. As I was inflating up to recommend sidewall pressure of 40psi it exploded (last check was 33 and I filled another couple seconds)
• second time was three days later with replacement tube bought from local bike shop and the regulator set to 50psi - I filled to 35psi and less than a minute later it exploded.
• third tube was genuine Continental and initially was ok inflated to 30psi. My wife broke her foot (unrelated) shortly after this and didn't use her bike the rest of the summer. This weekend, she was ready to ride again but the tire was low - I inflated to 32psi and 30 seconds later it exploded again.

All tubes have been the recommended size for the tire/rim and the explosions have happened at below the recommended tire pressure. I have verified the accuracy of my gauge by comparing to both the TPMS in my car and a certified gauge at work. Tired in the four other bikes in my garage have fine.

Any ideas to look for before I sacrifice another tube?

I would recommend using a hand-pump - sounds like these tubes aren't liking the volume of air being delivered by the compressor.

Look for the pinch point or sharp spoke on the rim. Look at the inside of the tire too. Is there a bit of nail or staple stuck in there?

Sounds like the fault of the rim or tire to me as well.

There is a rim-strip installed, correct?

Have you tried a different tire? It's possible there's something sharp poked just far enough through the tread to eventuall cause a flat.

If you remove the tire completely, flip it inside-out, and run your hand slowly all the way around the inside(now on the outside ) you should be able to feel it.

I once had a dirt bike that kept eating rear tubes, could not find a cause. I finally replaced the rear tire since it was worn, problem quit. One Saturday afternoon I was bored, got to looking very closely at the old tire. I found a big thorn that was embedded in the carcass, maybe 1/16 inch was sticking out. It was dark colored so it was damn near invisible, I found it by touch.

Yeah, this is a tire or wheel issue, not a tube or compressor issue.

Curmudgeon wrote: I once had a dirt bike that kept eating rear tubes, could not find a cause. I finally replaced the rear tire since it was worn, problem quit. One Saturday afternoon I was bored, got to looking very closely at the old tire. I found a big thorn that was embedded in the carcass, maybe 1/16 inch was sticking out. It was dark colored so it was damn near invisible, I found it by touch.

Yep, from my MTB days I learned to carefully check the whole inner tire surface by feel before putting in a new tube.

If it's a welded rim, check for a burr near the seam. I've also had thorns coming through the tires. Checking for either one is a good way to slice your fingers, so be careful. I always powder the new tubes and the inside of the tires before I install them, as it helps minimized pinch flats.

what they said above, except use something other than your finger to check the inside! last thing you want is some gross bit of debris (god forbid a bit of used needle) to cut your finger as you're running it around where you can't see..

bluej wrote: what they said above, except use something other than your finger to check the inside! last thing you want is some gross bit of debris (god forbid a bit of used needle) to cut your finger as you're running it around where you can't see..

Good point...I was only ever expecting thorns or maybe a shard of glass at worst. I figured finger cuts are cheap compared to inner tubes and the effort of changing them

That's most likely a bur on the rim surface. I've seen that exact behavior many times. Could also be a thorn or something in the tire. Check both (carefully) by touch. Even if you can't feel the burr on the rim, replace the rim tape. Use the clothe Velox type and make sure you get it wide enough on something like a beach cruiser with wider rims. If the tire feels okay, it probably is, but not necessarily true with the rim.

Or, and talcum powder the tubes before installing. And watch pinching the tube between tire and rim. I've done that a bunch too.

Don't disagree with the comments on the hidden/invisible burr/thorn/etc.

Would also like to toss out that really cheap rubber can burst with just a little bit of stretching. They are thin and sorta brittle. So if you're playing with cheapie tubes, you might want to step up to better tubes. After thoroughly checking the rim and tire for the above mentioned burrs, thorns, etc.

The rim protector tape: dirt bikes eat those things like crazy. I finally quit with them and ran a double layer of duct tape over the spoke nipple (heh heh heh he said nipple) heads. Lasted much longer.

Also look at the bead of the tire. We had a couple walmart cheapoes come through the bike shop I worked at that had, for lack of a better description, rolled beads. The lip on the rim was not sharp but actually too smooth, and the slight warpage of the bead in the tire meant it would slowly work off the rim at full pressure. We wound up replacing the tire on the one bike, but the other cuss-tomer refused to put a $30 bike shop tire on their $85 Walmart bike. We scuffed up the wheel rim bead surface with some 80 grit sandpaper to give it something to hold on to, and didn't fill the tire until the customer was actually at the counter. It held long enough for them to pay and get it in the back of their truck, beyond that I do not know...

Best thing I've ever used to check for tiny sharp things on the rim or in the tire is a cotton ball. It will snag on anything protruding, no matter how small.

At this point, I had pretty much assumed there was something sharp in the tire - I did a quick look-over after the first two explosions but didn't do a feel test (I like the cotton ball idea).

The rim tape is another thing I'll definitely check out.

Thanks, everybody!

Sprinkle talcum powder inside the tire, allows the tube to get comfy.

GameboyRMH wrote:

Curmudgeon wrote: I once had a dirt bike that kept eating rear tubes, could not find a cause. I finally replaced the rear tire since it was worn, problem quit. One Saturday afternoon I was bored, got to looking very closely at the old tire. I found a big thorn that was embedded in the carcass, maybe 1/16 inch was sticking out. It was dark colored so it was damn near invisible, I found it by touch.

Yep, from my MTB days I learned to carefully check the whole inner tire surface by feel before putting in a new tube.

Riding from Flint to Boston I had 6 flats in 12 days. The last day of the ride I had 3 flats in 1 block. The last time I fixed it I found the 1/16" tip of a thorn, with my finger. It helped to turn the tire inside out to find it. The tire was a well worn 26X 1.75 slick. My brother sat in the shade laughing, he had ridden from Seattle without a single flat tire

Sounds like you're not getting the tire bead seated on the rim correctly. Explosions (while not riding) usually only occur if the bead slips off the rim. The tube bubbles out the side and balloons that section of the tube until it bursts. It happens much more frequently on cheap wide steel rims than it does on higher quality bikes with narrow rims and aluminum rims with a better seat for the bead than rolled chrome steel sheet metal. If not seated properly it can take time for the tire to creep before the blowout.

There's a thin raised line in the tire mold by the tire bead. Fill the tire to 1/2-3/4 pressure listed on the tire and push/pull the tire carcass in or out of the rim till the thin line is even all around the rim on both sides of the tire and fill SLOWLY to recommended pressure checking bead while filling. Bike pump better than compressor.

Filling tires with the bike upright holding the weight of the bike is an easy way to get the tire not seated correctly. The weight of the bike pushes the tire into the rim farther on the bottom and the top slides out a little.

There's also relatively rare cases where the tube will explode because of increase in pressure causing the tire to be pushed off the rim the same way because the tire limit is exceeded. It can happen in the winter by filling tire in cold garage then bringing bike insde to ride on a trainer. Worst case I saw was a guy who brought a road bike in my shop for service. Put it in the back of a small hatchback and went to Walmart. It was a hot sunny summer day and the 120 PSI we put in tires must have gone waaay up. Tire was warmest (most pliable)right where it was touching the hatch glass and blew taking out the hatch glass with it.

This is a tool just for seating bike tires (although I've found many other purposes for it over the years). Beach cruiser tires are low pressure and rarely ever need the tool.

[URL=http://s240.photobucket.com/user/NOTATA/media/001_zpsjqp1nns1.jpg.html][/URL]

Looked closely last night and could not find any thorns or other potential penetrating foreign objects.

I did, however, notice for the first time that a small chunk of the tire bead is missing - which could certainly cause an issue as the tube is inflated and tries to squeeze its way in there.

So, I guess I'll be buying a new tire to go with a new tube this time.

Ah... happy half of my bikes are now tubeless... hopefully all of them will be within the next couple of years.

Curmudgeon wrote: The rim protector tape: dirt bikes eat those things like crazy. I finally quit with them and ran a double layer of duct tape over the spoke nipple (heh heh heh he said nipple) heads. Lasted much longer.

Yes. I've been using electrical or ductape for years. I have had good success with Pedro's rim strips

Explosion vs. popped/leaked is the clue. It's nearly always a tire that unbeads, often due to it having been blown off in the past due to over pressure of incorrect seating. A cheap steel rim doesn't help either.

New tire, fiberglass filement tape as a rim strip, plenty of talc.

Yep, if a section of the rubber covering the tyre bead is missing, it will creep off the rim at that spot, causing an explosion of the tube during inflation if not caught in time. New tyre time! Before you buy the new tyre and tube, go ahead and inspect the rim strip - this is usually a rubber, plastic or cloth band that covers up the spoke holes on the tyre side of the rim. If any spoke holes are showing, even a tiny bit, shift that rim tape ove to completely cover the holes. It is possible that it got shifted around wit all the fireworks going off .