Well, I put S rated 55 series tires on the '11 and it made no difference in ride, still hard as a rock, and those tires when standing upright could be turned inside out when pushing on the tread. Also one could go to a larger sidewall, end up with a V rated XL tire and the ride would still be hard as a rock, if not harder
Also, not to be picky, but you state great cars, zero issues, but you had to have the engine replaced in the SX, and to me that's a pretty big problem. The VDC sucks, and let's not forget about the poorly designed turbo oil line that needed to be replaced, steering coupler that was junk and needed replacement, oil mix they sprayed under the cars because of excessive rust, and as I stated early, engine so bad that they give a lifetime warranty if the KSDS update has been done, just another way to give the owners the shaft, not a recall, an update.
At 224k I'm on my 4th nav unit, all rear suspension parts needed to be cut out, frozen solid, exhaust system rotted out, brake sliders terrible and even the rubber on the sliders expands and sticks, so just eliminate them, guess Kia never thought of that problem.
Terrible company, terrible product.