Originally Posted by DEpointfive0

I think they also do 18's because tires are cheaper and if you go with a small side wall, it makes the acceleration of the car quicker (Its like changing the gear ratio)
The issue with 20's on our cars is that you have .5" less of a sidewall (Compared 275/35R19 vs 275/30R19 which is almost the same diameter), while that IS less flex/roll (but sometimes it's not a bad thing), it makes the biggest difference in day to day street driving, you'll FEEL a LOT more because the sidewall has less give and the PSI of the tires is more

So, IMO, 19" is the happy medium. I hate the tire costs, but at the same time i wouldn't go to 18's because I like the form over function of 19's