Greetings, Another, perhaps less involved, option is to go for smaller wheel rims…from 15 inch to 14 inch…with a corresponding increase in tyre (sidewall) size. The idea being the bigger sidewall will give more flex and so a softer (or perhaps better described as a less firm) ride. The bolt patterns, offsets etc are given in the link. I have found these to be the same to some other small Japanese cars such as older models of the Nissan Micra, though you should check for yourself to be sure. 2007 Daihatsu Copen - Wheel & Tire Sizes, PCD, Offset and Rims specs
