I have a 2012 Mercedes B200CDI with 18-inch wheels and runflat tyres and, needless to say, the ride is somewhat harsh and I would like to fit more comfortable tyres. I have considered changing to 17-inch wheels with 225-45x17-inch tyres. Would it be possible to retain the 18-inch wheels and fit more comfortable tyres?
Switching from run-flats will help but could be quite costly. It would be best to get smaller wheels with higher-profile tyres, and definitely not anything with an aggressive 45-series profile.