You sure you want 'rims'? Why not get some nice 18 inch wheels instead of ghetto-ing the impala. The rubber for them can get expensive real quick because 20 inch + wheels are almost all high performance types (and low profiles make the price go ^). If they get scratched, you're out all that money cuz they won't sell back value, they ride stiffer - not as comfortable than 18 in or less wheels, and can be structurally cracked easier than smaller ones - then they'll need to be replaced. You are looking at from 1/2 to three times the tire price going from 18 to 20 in wheels. Not to mention the price of the 'rims'.
