[TerryH]

I have the same problem...bought all new tires and tubes about 2 years ago...should have kept my 18 year old tubes that never leaked. All 5 of the new ones leak about 4 lbs in 10 days or so. I have tried replacing the cores, and tightening the valves, but nothing works. I suspect that these are some of the awful Chinese made products, made to inferior specifications. So far I just keep airing them up, but will need to replace with Walt's tubes down the road.