Hi Terence,
I bought my first Jag in Oct 2017, a 62 plate XF Sportbrake Portfolio with only 25K on the clock, I was expecting the magic carpet ride so was a little dissapointed with the harsh ride, a little research and a bit more spending and now I have it right.
It came with 19" wheels and 245/40 tyres, which whilst they look great were a big contributor to the harsh ride, add to this that the Sportbrake has self leveling rear air suspension.
I managed to find some original second hand 17" XF wheels on here, powder coated black, which matches the car, they came with 235/55 Dunlop winter tyres, this made an immediate improvement but I didn't really like the feel of the Dunlops, I bought some Nokian Weatherproof all season tyres and now it feels like silk, quieter, smoother, gripier, better in wet, better in snow, better in the dry, I really couldn't recommend the Nokians enough and they are cheaper than Dunlops, Michelin and Pirelli.
If you want some I highly recommend buying them direct from the UK suppliers at nordic tyres dot co dot uk and getting them delivered directly to your local tyre fitter, don't buy from one of those online companies that pretend to be in the UK but are somewhere in Europe that typically have older stock tyres and get orders wrong.
IF you look at all those older gorgeous Jags, none of them had low profile tyres, that's the key, remember, the tryres are the only thing in contact with the tarmac so it is vital to get that part right.
I hope my rambling helps.
Best wishes and happy motoring,
Dom,
P.S. I have kept the original wheels for when I decide to trade in for a newer model, @ £500 per wheel I didn't want to get them damaged, 2 birds, 1 stone.