Originally Posted by
NJC9452
Only this one rear tire is having issues because the original tube had it valve snapped open while I was trying to fill it with some more air because it was low on air. I had to have the tube replaced and the bike shoppe replaced it with a Kenda tube that promptly went flat all by itself while the bike was sitting on my back porch. I was mystified how the tire could have gone completely flat in three days while the bike was just sitting there parked. The man at the bike shoppe had filled it with air himself after replacing my tube and had filled it within the recommended pressure stated on the side of the tire. I tried pumping it back up but it wouldn't hold any air so I had to take it back to the bike shoppe and a different salesman replaced it with yet another Kenda tube. It was late at night and raining so I gently leaned the tire against the wall in my hallway and planned to put it back on my bike the next morning. Shortly after I woke the next day I heard a loud air noise very similar to tractor trailer air brakes. I went to investigate and found the tire completely flat! Somehow the tube had burst. I think that brand of tubes are just rubbish

I tried buying a different brand of tube at WalMart but the boxes didn't state the sizes like are written on the side of the tire.
The quality of the tubes on its own cannot explain all those happenings. (Though presumably the quality of the tube-rim-tire combination can.) There is something wrong there that has not been corrected. As Doohickie said, one needs to carry out an investigation to identify a cause, after each flat. Maybe the hole in the rim is not properly deburred, maybe the protective plastic sleeve is too narrow somewhere and the tube can touch the end area of a spoke. Maybe there is a piece of glass stuck in the tire. Without an identification of the cause and its correction, you will not move forward. Besides there being something systematic, causing the flats, you might have also been unlucky snapping the valve. Combinations of issues are not uncommon.