Originally Posted by
jimmuller
Is this true? I had a tire pop off once this past summer. I'd pumped a new 115psi-rated tire to 120, figuring it would lose some air when I took the pump head off. Admittedly this was an old non-hooked-bead rim. ...
It was exposed to the sun but the time was about 6PM so the sun was quite low and the temperature was falling slowly. About 20 minutes later the tire popped off the rim with a loud BANG! right where I'd been cleaning the rim. Maybe some alcohol seeped under the bead. In any case, I assumed the high pressure was a contributor. I've since ridden that tire many miles but never pumped it up quite as aggressively again.
With the litigious nature of our society nowadays, no manufacturer in their right mind would rate a tyre at 115psi that would actually pop off at 120psi. After you installed the tyre did you do this:
- let out all the air
- push the valve-stem up into the tyre all the way
- pull the tyre sideways and inspect the gap between the tyre and rim edge
- move over 20cm and pull tyre over again and inspect gap
- work your way all around the rim, then inspect the other side of the tyre
- only then with no tube visible anywhere, inflate the tyre
Without doing the final-inspection step, you simply cannot be sure that you didn't pinch the tube. In my early days, I've used many a road-tyre on my track-bike (anyone remember the 700x18c tyre-craze of the late '80s?). Specialized TurboR slicks were pretty common and the sidewall pressure said 130psi max. I'd pump those puppies up to 200psi all the time without any problems.
Here's some good sites on tyre-pressure:
http://www.sheldonbrown.com/tires.html
http://www.sheldonbrown.com/rinard/tirebead.htm