Ron Harry

Wasn't sure where to post this, but I've come across a 'new' problem I hadn't experienced before [I've been riding performance road bikes for at least a dozen years, so I've seen my fair share of tire problems].

In the last two weeks, I've experienced the clincher function of several tires [or rims] 'fail' after inflating the tire, of course, causing a 'blow out' of the tube. The tire just pops out of the rim.

This has happened 3 times now, with 3 different tires and different rims. The tires were all 23 mm. Two of the tires were gatorskins, the other rubino pro. The clincher rims have operated fine for several years with no problems.

One time, and I assumed I did not seat the tire properly in the rim [it happens I suppose]. Twice, I assume just bad luck. But 3 times on 3 different tires...and now I'm concerned I'm doing something wrong? But why now, after all these years, and countless tire changes?

The one thing common to the tires were that they were relatively new; the gatorskins totally new, while the rubino pro maybe a few hundred miles on it. They are all rated for 120 psi, which is what I inflate to. At least twice the failures were delayed; that is, several minutes AFTER I inflated...say after 10 minutes or more had gone by.

I think that's what's scary to me; that everything 'looks' fine but can fail 'later on'.

It must be I was not seating the tires properly, but now I'm sort of concerned and gunshy, that I could have a 'blow out' if the clincher function fails at +30mph careening on a downhill or something. Needless to say, I'm double and triple checking the seating now [which I did anyway]. Common flats are just a nusiance...but 'blow outs' I think could be dangerous.

Any ideas or advice on this? Could I treat inside of rims somehow to ensure 'sticking' power of tire clinch? It's really a puzzle why this is happening all of a sudden. The 'kapow' of these things blowing out is like a gun going off, .

vnF12

I had this happen with marathon pluses when I inflated them to max pressure on hooked rims (delayed). I just don't inflate them to max anymore, 100 instead of 110. They are a little different since they want to pop out in general.
I would check the rim for any dings or maybe your rim strip/liner got moved so it's taking up some space on the side where the tire should go. Other than that the rims might not have enough lip to grab the tire for its max pressure.

Bill Kapaun

Is it the same rim or different rims?
Might want to check the accuracy of your pressure gauge?

Al1943

This can happen if any part of the tube is caught between the tire bead and the rim, even if it is caught between the bead and the bottom of the rim. Try adding a small amount of air to the tube before installing. The amount of air I can blow into a tube using my mouth is just right.

Ex Pres 

+1 This was my first thought as well. Do the blowouts result in a nice slit in the tube?

Ron Harry

actually, yes, they do blow out creating a 'slit' almost like a knife cut. I had been 'deflating' the small amount of air to get the tubes on the rim, just to help get the tire bead back over the rim, so that makes sense about the pinching between tire bead and rim. I will assume that was what I was doing wrong.

Ideas presented are appreciated. After thinking, I think I may have been inflating above the max design pressure on the gatorskins also. The Rubino Pro was probably just a bad seat by me. I'm backing off about 10psi, and so far, no more problems. The bad guage would make sense too.

But that brings up another question about 'maximum' pressure these tires can take. I always assumed there was a fair amount of headroom in their design. This has been a hot summer, and I can only imagine how, once upon a hot road, the real operating pressures in these tires become. If I inflate to 120 psi in a nice cool room, I can only wonder what that pressure will be a few miles out in 99F weather on black asphalt road. It's been so hot at times it has actually concerned me this year. Can a hot road blow a tire out? I'm sure those out west, say in Arizona, must have a better handle on this. But I don't hear of blow outs happening due to heat expansion of tire inflation. It would be a great liability for these tire companies if that happened; so, the 'headroom' assumed?

davidad

The sidewall pressure is 1/2 the pressure necessary to blow the tire off of the rim. The pressure you inflate to on your bike depends on the total weight of the vehicle (rider and bike). https://www.adventurecycling.org/res...SIRX_Heine.pdf

MGmech

I wouldn't have thought 120 psi would be too much pressure if the tube is properly fitted. Expansion is a problem in your case because (we'll assume) the tube is trapped under the bead of the tyre and has space to expand. Changing a tube is simple enough, BUT there is a procedure to follow and plenty of people don't know how to do it properly. We've tried to make it clear exactly how to do it properly in this guide

https://www.madegood.org/bikes/librar...ire-bead-tyre/

Bill Kapaun

I don't think heat is the problem by raising pressure.
It's likely more of a problem by softening the tire bead.

FBinNY 

It could be poor seating, or a design mismatch between the tire and rim. Most of today's HP tires need a hook edge rim to withstand the rated pressure, conversely, there are still a few designed around straight side rims, which can be difficult to seat on a hooked rim.

One way to tell the difference is to look at the tire. On tires designed to take full advantage of a hooked rim, the bead area bulges beyond the outer face of the tire slightly. That lets pressure push the bead under the hook forming a mechanical interlock. I'm not saying that a tire without a visible hook won't seat, just that it's not as secure a fit.

The other possibility remains poor seating, or trapping the tube between the rim and tire. Since you're experienced, I won't rehash tire mounting 101, but suggest that you consider mounting the 2nd side starting opposite, and working down both sides to the valve. The advantage is two fold. First it allows the tire to move to the deepest part of the rim's center well so you have more slack to finish. (tire must be massaged back to even distribution afterward). Second, ending at the valve means that if tube is trapped, it can be freed by pushing the valve in taking the tube deeper into the tire, then pulled down assuring that the tube is well inside the tire.

As you point out, different tires & different rims argues against a defect, so it's likely something you did, and you need to take your time, checking your work to prevent a 4th blow.

lostarchitect 

What is the common denominator?

Have you used the same pump all 3 times?

bobotech

Is it remotely possible that you were using 27 1/4 inch tires on a 700c wheel? I have seen that attempted however what usually happens it that the tire pops off way before you get to any significant pressures.

onespeedbiker

+2 What the OP is describing is exactly what you would experience if you are trapping the tube under the tire bead. When you inflate the tube, when it is under the tire bead, the air pressure will mount until it is sufficient to blow the tube, leaving a slit in the tire. Further, since the pinch is at the location were the wire bead seats into the tire clincher channel, it does not allow the bead to seat and the tire can blow off the rim; I'm not sure of the actual sequence but but there's a big bang! and the tire blows off leaving a clean slit in the tube. New tires, especially wire bead, are pron to this or any tire that is so difficult to mount that you need tire levers to get it on. The solution is actually fairly easy; after you have mounted the tire, pull the side wall of the tire away from the inside of the tire rim and make sure you see no part of the tube coming out from under the tire; this will usually happen at the place where you completed mounting the tire on the rim, but I would check the entire tire just in case.

lunacycle

In addition to that posted above, I have noticed that by coating the tube and inside tire with baby powder, the tube is easier to situate, and it makes future tire removal easier as well.

DannoXYZ 

It's vitally important that you start pushing over the tyre at a spot AWAY from the valve stem. Then go over the valve stem area along the way. Then after the tyre is completely on , shove the stem into the rim and tyre to unpinch the tube in that area.

Now comes the MOST IMPORTANT PART. Pull the tyre sideways so that you can inspect the gap between the tyre and rim. No tube should be visible. Move over about 6 inches and pull the tyre sideways again and inspect. Repeat all the way around the rim and repeat for the other side of the tyre . No tube should be visible. Only THEN do you pump it up . With a floor pump only, no hand pumps allowed.