Failed within 24 hours on 45mm tires. Postmortem showed failure at the nonelastic reinforcement opposite the valve. This area will not stretch when fully inflated, leaving two sharp wear points. These are probably good up to about 38mm tires.
I had four flats within two weeks against the inside of the rim with brand K. I ordered a couple of these Continental Tours and a couple of Michelin Airstops to see if it was the fault of my rimrim tape (I never could find any problem with the rim or tape) or if it was the fault of the tube. I put in the Continental and it has been over 30 days and 400 miles of riding and I haven't had a flat (so I haven't tried the Airstop yet). The overall quality of the butyl, the seams, and the valve look better than brand K also.
These were installed on my touring bike rebuild. I wanted durable, quality tubes at a reasonable price. They are holding up very well!
Installed the tube on new tires purchased at the same time. If you need a refresher on how to install tubes, read the instructions on the website before you damage the tube. I have had the tubes in for over 2 months now and have not need to add air. My tire are 700c x 42mm. I have put on about 100 miles, so not very much. Tube is holding up well and I like the metal stem.
Tubes are tubes, right?
Seriously, I like that these are a bit thicker. I don't race. I'm not concerned about weight. I just like to think I'm going to go out and ride and come back without flatting. If these contribute at all to my security, they're worth it.
Also, I'm a traditionalist. I like that Conti uses a steel stem with a securing nut. Classic!