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.
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.
These were installed on my touring bike rebuild. I wanted durable, quality tubes at a reasonable price. They are holding up very well!
I have used a variety of inner tubes over the last 50 years, but the Continental Tour 700 IMO is the best and a decent value as well. In thousands of miles I have yet to see any failure at the stem area (a weak point in any tube) nor have I had any pinch flats. I check the air pressure in both tires before every ride. All tubes leak and these are on the low end. I only need to add air ever other ride.
Just mount them with some talc powder and off you go! No worries.