Bulging Tire / Sidewall
 

I picked up an 80s steel road bike a few months ago. After riding on a pair of 700 x 25c tires, I decided to try a pair of 700 x 23c's (Continental Ultra Race).

The rear tire went first, in about 100 miles. Not 100% sure what happened, but I think I got a pinch flat. When it popped, it went off like a shot, blew out the sidewall and obviously destroyed the tire.

About 100 - 150 miles later, the front tire is having issues. I was riding along, no particularly bad bumps, and the tire bulged outside of the rim on both sides. I stopped immediately, deflated the tube, re-seated the tire, re-inflated it, no problems, didn't really think about it.

Today, riding on some moderately rough roads but nothing too bad -- I didn't hit anything worse than train tracks. Got another flat; swapped the tube; and when I re-inflated, the tire bulged over the rim right at the valve. Deflated the tube, moved the tire, reinflated, bulge at the same spot. Did it a 3rd time inflating very slowly and it was ok. (The previous major bulge was NOT at the valve iirc).

BTW, no problems like this until I put the Continental tires on -- just one puncture flat in about 1000 miles.

So does this sound like shoddy tire construction, or an issue with the wheel(s)? Is there a way to figure this out other than taking it into my LBS and having them check it out?

Do your rims have "hook" beads or straight wall?
Pic from Sheldon's site-
http://sheldonbrown.com/images/bead-seat-diameter.jpg

They look the same as in the illustration, which I assume is "hook."

FYI, the tires are foldable. I normally inflate them to around 110, which is the official recommended pressure.

No, it's just an issue sometimes when putting tires on. You really have nothing to worry about. Just recheck the tire and make sure the sidewalls aren't damaged and you're good to go.

OK. Next time you mount the tire, make sure that the tube is inside the tire all the way around and not pinched between the tire wall and the rim, as I am sure you did. That's an easy one.

THEN- and this is the important part - once the tire is on the rim, inflate the tire just a little so that it is fairly soft. Go around the tire and push the tire down onto the rim with the palm of your hand. This will help seat the tire bead under the rim hook.

Also, be sure to push the valve back down into the tire when the tire is still soft. Then re-inflate (of course, making sure the valve pops back up out of the rim hole).

Ok, done.... So bulging like this is typically just a result of bad tire technique, rather than something wrong with the spokes / rim or a bad tire?

Pretty much. If you have a damaged rim, it can be a problem. ZB, if you have a flared-out section of rim. One ding usually is not enough to cause a problem.