I could never understand the need for the current trend of the fitting huge wheels with low profile tyres.
Give me big fat tyres any day as they are much smoother on the road, remember the XJ6 when it was launched, (well maybe not lol) where the rider was super smooth.
Put on top of this, the current state of our roads and there lies the problem.
I’m sure the standard fit would be 19” the same as fitted on my CLS Shooting Brake but even with these the ride can be very firm especially on our rough roads.
My SL (2004) is fitted with 17” with bigger tyres and the ride is much smoother. I was tempted to upgrade the wheels to a more modern style but have changed my mind as I don’t want to impart the ride and spoil things.
Have a word with your local tyre specialist who may be able to supply tyres with a larger profile to improve things. I would certainly aim for a matched set as I always feel tyres of a different make and pattern work against each other. You don’t see Lewis Hamilton going out with a mixed set do you !