Smallest possible rim size & software fk8

Hello everyone, the fk8 is to be ordered next week and in the run of the next 3-4 years / ~230 tkm on the balkan are operated? the streets have many impact holes, unevennesses, cracks. according to online configurator the type R is sold only with 20″ wheels in Bulgaria, on German honda pages I found 18″ wheels. my current car had from house 18″ wheels, which were very difficult to drive here, the change to 17″ brought a significant improvement. can someone tell me which mass the 18″ tyres should get, and whether one (the German TÜV once left outside) can convert it to 17″ wheels, too? in the conversion of the drive from “sport” to “comfort” should be guided and gaspedal to be softer, more fussy, with more play – can one turn this “control program” without a honexterner tuner turn on it?