OEMs do a lot of engineering work to "tune" the ride quality to the frequency transmission characteristics of the design tires. Suspension and subframe bushing design and durometer are specifically tuned to attentuate the primary frequencies transmitted by the tires. Tires are an integral part of the suspension and substituting short/stiff sidewall tires will normally dramatically increase ride harshness, so you have to be willing to accept this for the "look" and performance increase.

For some, it's not a good tradeoff.

Duke