Black Beast said:
Does anyone know the answer to my question? I'm thinking about bidding on the rims but scared of losing performance.
There was a study done a while ago, where one of the car rags tested handling characteristics of various sized rims (15"-19") with the same width tires.
The best handling wheel size was a 17" rim, followed by an 18" rim, then a 16" rim, then the 15" rim, then the 19" rim was dead last. With a 20" rim, your handling would be worse than the 19" rim. Take this "study" with a grain of salt though, because car rags aren't always right.
Here are some things to consider.
If the bigger wheels/tires weigh more than the stockers (which they probably do), they will slow your car down a bit. My guess would be .1 ET and 1 mph in the 1/4 mile. You would probably see a few rwhp loss on the dyno from the extra rotating mass. Traction will be much harder to achieve than before because of the loss of sidewall (tire height) Wider tires help, but taller is better than wider from a traction perspective (in most cases).