Tyre won't seat nicely - bead too short?

Success! Just tried this. Diluted a little washing up liquid with a little water. Wearing a nitrile glove, and with wheel flat on floor, tyre fitted but with inner tube deflated, it was easy to smear liquid along the bead with a finger, then flip the wheel over to do the other side. The tyres have a max. inflation pressure of 85 psi, and I went up to 100. Rear tyre went "pop", and bead was seated nicely. Front tyre had a spot where the bead refused to pop out. I deflated it again, put more liquid over the spot which refused to emerge, and re-inflated to 100 psi. Bead still didn't pop out. In desperation I pressed on it with the rounded, blunt end of a plastic tyre lever, and it eased out into place. Let tyres down to working pressure of 55 psi front / 60 rear, and the beads stayed in place. There's a tiny ridge on the tyre at the edge of the area which is designed to contact the rim, and I think this might have been catching on the edge of the rim, preventing it from seating properly.

Thanks, I'll give that a try. (Though in my case it will have to be Ecover!)