Hi Edwin,
I have 2011 XF-S with the 20" wheels. Soon after I bought it in October 2018 I had to replace the tyres as those fitted (Chinese 'Triangle' brand) were simply not up to the job in the wet and not much better in the dry.
I went for Pirelli P-Zeros and the car was transformed.
It's now about 15,000 miles later and there's still some life left in all four of them after a mixture of long motorway trips, local shopping trips and everything in between.
Good luck with the XF-S if you go for it, I take mine for a spin just for the hell of it most days!
Cheers,
Jon