LDNN

Your car is new so chances are the tires are OEM. Stick to the recommended pressure. I worked for Michelin a few years, I remember the Honda/Toyota engineers would come and "tune" the tires to the car before we put them in production. Point is they optimize the tires for your car with hard science. I wouldn't go changing tires or pressure just because.

azndriver

With regards to the tires

seeing you are using

Dunlop SP Sport 2050
Front: 225/40/18
Rear: 255/40/18

To help with the ride, the rear you could go down to a 245/45/18 tire, as the 40 series tire does ride a bit more harsh due to the thinner side wall...

If you car is stock height, you could possibly get away with a 225/45/18 in the front...

MyIS350G

iTrader: (6)

go with 17" wheels and fatter tires if the roads r bad where u live. That will smoothing the ride

kingCUONG

Good info. Thanks guys.

4TehNguyen

iTrader: (1)

youre going to have to go change to 17" wheels and thicker tires if you want a smoother ride. IS was meant to be a sporty car so you will have a stiffer suspension