Got new tires and tubes for my Univega. Tires are 27x1 1/4. This is the second freakin tube that has popped while the bike is just sitting there. And yes 90 psi fir these Kenda tires. Tubes are Kenda 700x28/32c-27x1-1/8x1-1/4. The only difference i can see is the Kenda sits a little higher in the rim than the really old tires that were on it.

Are the rims straight wall or hooked bead? Do the tubes push out from under the tires and then burst or are you describing flats cause by small holes in the tubes?

Yeah, what kind of "pop" are we talking about?

One situation that often arises is tubes failing (rupturing) on the rim side, to either side of the valve-stem "pad", due to the thicker rubber not easily falling fully into a narrow rim's inside cavity, so the thinner rubber to each side of the pad ruptures as the tube's thinner rubber is pushed deep into the rim cavity by air pressure. The cure for this can be a combination of a larger-section inner tube and/or giving the valve a tug as the tire is just starting to be inflated, before air pressure pins the tube against the inside of the tire casing. Wider tires on narrower rims create an outward-jutting sidewall that creates a step or "inside corner" in the inner shape of the tire/rim space, which the tube must get dragged past in order for narrower tube to fully expand into the rim cavity without too much localized stretching.

So first thing is to note whether the tube failures are happening in the same location relative to the rim and valve.

Yes, what is showing from the tube(s)?

Is there rim tape on the rims, is it in good shape, and if so, does it cover the nipples?

I'd bet they are non-hook bead rims and cannot hold 90 PSI.

Yes...I was wrapping bar tape after airing tires up and I heard this sliding under pressure sound and I am like 'what is that sound' PPPOOOOWWWW!!! I said a few words...finished my bar wrap then put the bike in garage. Picked up my other bike to go for a ride closed garage door and PPPOOOOWWWW!!! The other freakin one blows...I am beyond pissed!

If the wheels ar 27" and it is a mid to low end Univega (still a nice bike!) the rims probably do not have hooks on the edges to hold higher pressure tires on the rim. As such, no matter what the tire might say, you can't go above 80 psi (in my experience) or you run the risk of repeating the blow outs.

But, is the tire flying out of its seat in the rim?
Or are the inner tunes popping inside a still seated tire?

the tube is pushing itself out and busts and tire comes off rim...they are not busting inside the tire.

Does that look normal...of course this was before it popped and I aired them up to 90 psi. I actually road 6 miles on them earlier this week but they only had maybe 60-70 psi in them because my little air compressor has a leak and that is all she would put in them.

Take the hint. try 75 max

Yup, the tire can handle 90, but the rim can't.

When you keep popping tubes (especially for unknown reasons), it is time for a new set of tires. You'll go mad trying to figure out why the tubes keep popping, just get the new tires.

If you're dealing with straight walls, keep it under 75 max. If you want smooth on those rims, get bigger volume tires.

Schwinn originally spec'd the 27" for a hookless (smooth sided) rim and 75psi. There is nothing to keep the tire in place as higher pressures push it off, then ....KABLUEY!!... (or what I imagine a 38 sounds like going off, my ears are still ringing). The 27" has been modernized with hooked rims but there are a lot of old bikes out there with the hookless rims (I thought is was mostly a Schwinn thing)

I kept blowing tubes a couple years back. The damn Chinese tubes are cheap crap. It's really loud when they pop. Scary. So, I gave up. Been using very heavy "thorn resistant" tubes on all my wheels the last few years. These thorn resistant tubes are very heavy. Weigh as much as the tire. And expensive. Run about $10. But, haven't had one pop yet.

A different brand tire just might help. Probably not, but it might be worth a try. Besides, Kenda tires aren't the best.

They are brand new Kenda tires

its pretty loud...sounds more like a .410 single shot though

I'm gonna wear these out and try another set

Welp...learn something new everday. Ordering some more tubes and keep em at about 70 psi

I'm sorry to laugh at something terribly frustrating but that was funny.

I was recently in that same situation with putting a new set of skins on my 760. Wrecked one tube and made 3 patches before finding the sweet spot. Hang in there, good advice from the guys....my guess was a non-clincher rim as previously mentioned.

My fix was to buy some new 27" rims (Alex or Weinmann are inexpensive) and read up one wheel building (thanks Sheldon Brown). Swapping out rims is a easy way to get your feet wet in wheel building for the cost of a few tubes. Keeping it 27" minimizes the changes and expenses vs. "upgrading" it to 700c. Also springing for better tires is one of best ways to improve old 27" bikes. You don't need to go all out for Gatorskins or Marathons (unless you want to), but some SuperSports or (enter your favorite 27" tire here) will make a significant improvement. Wear out the Kendas this summer and rebuild the wheels next winter with new rims and the tires of your choice.

Hey! This is C&V, is there a thread for "Favorite 27 in tire?"

Sounds like a good plan...so just search for Alex or Weinnman

No worries...I was beyond pissed, the second one blowing was just icing on the cake...I put all my frustration into my workout and felt better after...it was funny then!

Weinmann 219 Rim 27 x 1-1/4 36 Hole Silver
or
Alex x404 27" 36 Hole Silver Rim

Sun CR-18 or M13 are a nice upgrade.
And count the spokes, probably 36 but check.