Definitely check the tyre pressures. They come from the factory with over 50psi in them from the factory so that they don't get flat spots while the car is standing. It's part of the pre-delivery inspection to lower the pressures to the correct level, but it wouldn't be the first car to escape a dealership with too much air in the tyres!
When they have 50psi in them it certainly makes the car rather unpleasant to drive - if the tyre pressures are normal, let us know... There is one other thing that could cause it, if your car came with a factory body kit... If necessary we can look in to that. It's unlikely though.
Accim is right, it also depends what car you last drove as to your perception of how the i30 handles and rides. Mine has 17 inch wheels/tyres though and I drive on roughish country roads all the time and can't fault the ride. My 80 year old grandmother comments every time she gets in the car just how comfortable it is.
