still have to cut the guards to fit 15s, unless you want to destroy your guards the first time you hit a bump whilst turning

and doubt that just the rim size would change the handling that much, weight and tire quality would be alot more important

that said, im not a fan of anything bigger than 15s....not that many cars seem to be able to pull it off. also maybe somehting to do with lots of 17s being gay looking rims anyway