If you upgrade to custom wheels and wider tires to improve your road handling then you'll need to consider adding fender flares to reduce the added drag.

When you add wider tires to your car to help with traction, you’ll need wider fenders to help deflect the air that will pool up in front of the exposed tire surface, causing drag. Wider tires also kick up more mud and debris onto the sides of your car’s fresh new paint job. Adding fender flares helps to clean up the airflow around the sides of the car as well as protects your paint job from mud and debris.

Extreme Dimensions offers fiberglass fender flares for the front and rear at around $170.00 a pair. You can also go with carbon fiber for an even more aggressive and custom look.