Tyre Help Needed!

I’m trying to reseat a tyre so that it sits evenly on the wheel - at the moment around 30cms of the bead is sitting lower on both sides than the rest of the tyre.
I’ve tried inflating and deflating several times, using a compressor and liquid soap. I’ve inflated it to 45psi too, but nothing is helping.
Any tips??

 

No haven’t had tyre off. It’s a cast wheel on a project bike I bought just before lockdown It hasn’t shown any signs of deflating but obviously I’ve hardly ridden it.....
Have had thought - maybe the lower section is better seated - I’m going by the moulded lines just above the bead......