I am getting back into bike rideing after many years... I am having a heck of a time trying to find decent tubes for a 709c X 38 rim... I"m using thorn resistant tubes and they seem to have a problem with the rubber coming apart aounnd the valve stem... I am on my third tube in about as many weeks.. Originally I had a brand on the tubes I had never heard of.. The last ones had a well known manufacturers name on them .... My LBS guy says it doesn't really matter what name is on them they all come from the same place.basically.... Does this mean it is no longer possible to by a quality'dependable tube ???.