Ditto S'prince about checking for rough metal around valve stem hole. And I just finger tight my lock rings. Is the rim a double wall or single wall and does it have reinforcing eyelets? Some single wall rims w/o eyelets have the issue of a narrow channel for the spoke nipples. If too narrow, it can cause excessive deformation of the base of the valve stem and it may delaminate over time. Some double wall rims without eyelets will drill the hole through two layers of metal rim. In both cases, making sure a good fitting rim strip that is aligned around the stem hole will help cushion and protect the tube.