In 20 years as a mechanic I never saw a blowout caused by a flat spot. Perhaps if the rim was both pushed flat and bulged out by an impact it would be unable to hold a tire, but in most all cases correct installation is the key.

Did you get the same width as before? A tire that is too narrow for the rim can blow off.

No, that is not likely at all, and it is apparent from the pic that the tire is not narrow, probably a 27 x 1 1/4 or so. The most likely cause is still mounting technique.

That doesn't mean much. Just because something is marked on a tire does not make it so in practice. When dealing with non-hooked rims, you most definitely want to use wire beaded (non-folding) tires (looks to be the case with the OP). You want to take care that you have the tire properly seated, as you describe. But, even then sometimes it just doesn't work out and you must run lower pressure. My JT tandem has 27 x 1 1/4" Weinmann concaves (non hooked) and I am simply not able to run wire-beaded Panaracer Pasela TGs over 85 psi.

Tire companies are fairly diligent about making sure their tires will perform at and above the rated max pressure. I keep seeing posts that it's impossible to maintain high pressure with straight sided rims, and that's simply not true.

But, your points are well taken. Straight side rims require tires designed for them. Those will have steel wire (usually mono-strand) beads, and the outer bead area will be made for seating on that rim pattern. One problem is that since most high end rims are hook edge the tires are designed around that, and often won't hold on a straight side rim.

But that's most, and not all. Interestingly, straight side rim users will probably have better luck with low to mid range tires of older designs. On the bright side these usually cost a third or less compared to the cool stuff.

A 27x1.25" tire hardly needs that much PSI, due to its Volume.


Weinmann concaves. are a C&V part , by now, so go conservative on the inflation,
and check that there is no Tube under the Bead when you pump it up.

a hard to install tire is better than an easy to fit one.. for security in use.

Do you know of a high pressure tire (90+ psi) that's currently produced that meets that criteria ?