Hi plc268
I pulled up one of my full res pics and it is a T155/70R19 113M. I've attached a few more pics from the E-Bay listing that made me think it might work.
I did a bit of searching back in June looking for part numbers etc at Hyundai but don't remember if all Equus's used the 19" or it...
A spare option for the S550 GT PP
If any one is interested I found that a spare from a 2013 Hyundai Equus will fit our performance pack cars front and rear. I did have to open up the hub hole by about 2.3mm but even just using my air die grinder and some sanding drums it wasn't too difficult...