FWIW, I generally run IRC tubes on my bikes, and have had good luck with them so far. I rarely need to add makeup air. On the other hand, I run Heidenau tubes and tires on my CL350. These tubes are made from natural rubber and have an inherant, very slight porosity. I air these up more frequently. They are heavy duty tubes, noticeably thicker than the IRC.
Jim, that is a tragic story!