Rim trapes will be of no use here as the spoke nipples are not in the well of the rim but off on one side. A tape would just ride down into the well and not cover the nipples at all. my concern with duct tape is getting it under the tyre bead, that would surely not be good. The nipples are all smooth, no sharp edges, I suspect the tyre, as it flexes, traps the tube on top of the nipples and sort of nibbles at it as the load comes on and off, especially when cornering. I will cut a section out of an old tyre tomorrow and see how it looks from the inside. surely I can't be the only one to have noticed this problem?