JakeRidesAgain

I'm having a fun little problem with my bike. It's an old Miyata 1000 I bought a few weeks ago off Craigslist, 27 1/4 inch tires. On my first ride out with it, the front tube blew out. On my second ride, the back tube blew out. In both cases, it was really forceful, almost like a gun shot, and it blew the tire right off the rim. I figured it was because there wasn't any real rim tape to speak of on the wheels (just a weird plastic strip?) so I bought some cloth rim tape and re-taped them. Now the front tire works fine, but the back tire keeps having blowouts when I put any real pressure in there.

A few extra bits of info:
-I couldn't find 27 1/4 inch tubes at REI, the guy there sold me some Presta 700cc 28-35 tubes and said they would work. It took 3 of those tubes to realize my bike needed a Schrader valve.
-Ever since the FIRST back tire blow out, I've had at least two more. In fact, that's the real problem, is this keeps recurring.
-I think this is a beadless rim/tire? I can take pictures tonight if it helps.

So obviously, my first idea was to source the correct size tubes, which I did. Same thing, I blew the tire up and kaboom, I ended up having to bum a ride to work.

What this whole long winded thing is coming down to is this: do I just need to buy new tires? Did the force of these blowouts create a bulge in the tire, giving the tube a place to squeak through the rim? Or is there another problem I'm not seeing?

Appreciate the input guys, and hopefully with your help I can figure this out.

HillRider

The rim strips aren't the culprit. Without seeing them I can't be sure but I expect your rear wheel doesn't have a hooked-bead rim and, therefore, won't retain any tire at much above 80 psi. You probably don't need new tires but may need new rims. A visit to an LBS will tell you for sure if you don't know what to look for.

Flying Merkel

Check the rim to make sure it doesn't have a flat spot. Had this happen to me. The tire stay on for a while, then slowly creep off and explode. Some cheap tires will blow off the rim under pressure. Scared the hell out myself on a downgrade under braking with this trick.

lostarchitect 

Do your tires have wire beads? If they don't, it'll be hard to keep them on a hookless rim at a decent pressure.

myrridin

It is also worth checking the tire as you gradually inflate it (off of the bike). It was doing this that allowed me to diagnose a small rip in my sidewall that was otherwise invisible.

HillRider

Even with wire beads, hookless rims won't retain them at high pressure. A friends early 70's Raleigh with hookless Weinemann 27" alloy rims wouldn't hold ANY tire above 85 psi.

JakeRidesAgain

Hookless rims! That's what I have, I was trying to think of the name. Like I said, I'll get some pictures tonight. They're cheap CST tires, probably ten bucks on amazon just so the guy would have something on there to tell with the bike. But the inner walls of the rim are smooth.

Pictures are in order, and I shan't disappoint. I'm really puzzled by this one. Guess I'll go ask the C&V guys what kind of tires I should be looking for.

lostarchitect 

I have no problem keeping wire beaded Panaracer Paselas on my hookless Fiamme yellow label rims at 100psi. But it will depend on the tire/rim combo, of course.

Regardless, you have a much better chance of them staying on with wire beads.

lostarchitect 

Is it this tire?
https://www.niagaracycle.com/product_...ucts_id=507968

Looks like it doesn't have a wire bead?

JakeRidesAgain

Lost: that looks about right. It's the right size, right color, and right PSI. Can I run a wire bead tire on a wheel that doesn't have hooks?

cycle_maven

With hookless rims, it's mighty important to get the tire centered on the rim. There should be a little raised portion of the sidewall above the bead (maybe just a mold flashing), and it should be even all the way around the rim. If it isn't, then POW! your tire blows out. At the worst time, usually. The tire needs to be installed, then a couple of pounds put in, then checked for evenness, then inflated more, etc. But yeah, you can run wire beads- in fact you can't (or shouldn't) use Kevlar beads with hookless rims.

CACycling

I had no trouble running 100 PSI on a couple of old Schwinns with hookless steel rims. Even commuted on one of the bikes for over a year.

Booger1

Wire bead tires will help,but you may still have problems if you want to run higher pressures than about 70-80 lbs.

I used to run more than that on my old Araya's, but I've had tire/rim combo's that didn't like it.

lostarchitect 

Yes, you SHOULD run wire bead tires on rims with no hooks. As others have said, you still might have some trouble, but that helps a lot. As cycle maven also notes, it's really important to get the tire centered as well.

brooklyn_bike

my friend had similar symptoms on their bike. it was either (i can't remember which) a too long spoke very slightly poking through the rim tape or a small bur of metal inside the rim. same results: tube was fine until it was pumped beyond a certain pressure and then immediate leak. check inside rim very carefully.

prathmann

I'm almost certain that the tires shown above from CST already have wire beads. Kevlar beaded tires are usually advertised as foldable and cost more. The advice to inflate in stages and to check that the tire is evenly seated is good. And with such wide tires (32mm) you shouldn't need to go to pressures of over 80 psi. The tube size isn't causing your problem - the tire bead is slowly working its way over the edge of the rim and letting the tube escape. At that point any tube will rapidly expand and blow up.

HillRider

That isn't the OP's problem. He isn't having leaks, he's having explosions from the tire crawling over the rim bead and leaving the tube unsupported.

JakeRidesAgain

This first one is actually from blowout #3....

Blowout #4, the 3rd on the rear tire.

neurocop

Definitely a problem with the rims/tire bead. Looks dangerous!

JReade

Does the rim tape go over the spoke nipples? It looks like a rusty nipple in this pic, which could be rubbing on the tube and popping it as soon as you inflate it.

fietsbob

mounting issues , are you inspecting the installation , to insure you have no inner tube
under the bead , rather than entirely between the tire beads.

carefully inflate by hand pump, and make sure the tire is evenly fitted..

JakeRidesAgain

I was real careful to make sure all spoke nipples were covered, and just went over the rim again to make sure there aren't any spots where spokes are poking through. I think what you're seeing is the rocks on the other side of the valve stem hole. When I first saw the picture, I thought the same things, which was why I pulled the tire off and gave it and the rim a thorough inspection.

mikezs

That's the valve hole, and it's the stones on the floor you can see through it.

Wolfwerx

As an aside: 700c tubes work just fine on 27" rims.

SBinNYC

According to https://sheldonbrown.com/japan.html#miyata the Miyata had 700c rims. If you are putting 27" tires on a 700c rim, then your experience is par for the course. You want to compare your wheel with a known 27" or 700c rim to confirm. The rear wheel in the picture is definitely a 40 spoke wheel, which is consistent with the Sheldon's specs. That was rather unusual, most bikes came with 36 spokes front and rear at that time.