So I managed to get one to seal! Unfortunately, my taping skills around the valve were somewhat lacking, so it’s gone flat, and I need to apply more tape…
SteveL – beads pretty loose, but won’t building up the tape just force the bead away from the rim edge and into the central trough?
Oldnpastit – I see your point, but I hate the idea of ditching pretty new tyres before their time… Not ruling it out, mind…