I also worried about getting stuff under the bead but I now think that the load at the base of the bead is lifted from the rim when the tyre is inflated and that the friction to hold the tyre from turning under braking is all on the side of the bead. It's very hard to know what is going on when you can't get in there to see!!!

2013 M3W 1960 Velocette Venom and the Landrovardo!