thank you to everyone who has replied to my post My bike is fairly new and I have hardly ridden it more than a few miles. It has the original rims and everything like came with it. I pried out the burst tube and found it has a little hole close to the valve but there is nothing inside of the tire that could have caused it, nothing sharp or anything. I have no problem with the other two tires that still have the original tubes that came with the bike. 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. Luckily it happened then and not after I'd ridden several miles from home. The man who'd replaced the tube had filled it within the recommended pressure stated on the side of the tire and had showed me while demonstrating a guage that he sold me so I'm sure it was not over-filled. 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. I got 26 inch but think that the other numbers are wrong. I had such a hassle trying to even get the tube into the tire and it didn't seem to fit as if the tube was much larger around than the rim/tire. Ugh. I couldn't get the tube in, much less filled I think maybe I should try those airless tires that were mentioned, though I'd have to replace my tires one at a time due to my budget. Thanks!