Alternative tyre sizes for DS5 19"wheels

Hi, I’m new here. Had my DS5 for a few months now, previously owning 3 other Citroëns.

My car has 235/40/19 tyres. I find the ride very hard.

Does anybody know if it is possible to fit 245/40/19 or even 255/40/19? to get a taller sidewall and a more comfortable ride.

I appreciate that there will be a small speedometer error.

Apologies if I have posted this in the wrong section.

Thanks