This might seem like an obvious question but I'm wondering if things could be different for the Z3? Currently I have stock 17" with ZRs. I'm wondering if the car would feel more twitchy if one were to go to 18" ZRs if they didn't upgrade suspension first? I'm thinking that this might be the last option on the list because the trade off of slightly firmer tires to a more twitchy ride would seeminlyg not be worth it? Also do bigger wheels do anything more than make the car look much cooler ? I guess BBS wheels prob weigh much less than beemer wheels which could help and also I'm sure people get wider wheels too. Anyway, Any comments or experiances with wheel upgrades?