What i have experienced over time is that car suspension is meant to handle hard/ big bumps where as softer bumps like pebbles etc are normally absorbed by additional cushions like seat foam etc. New Gen Corolla seats are hard compared to prev Gen and any JDM, thats why you feel pebbles and small bumps on road. I observed this from day 1 and i am hoping its seat will soften with passage of time.
So culprit is not just the tires i some times feel pity for Euros