Don't waste too much time on the lightweight wheels; lightweight wheels are only about 25% as important as lighter weight tires. Weight matters most the farther you get from the axle center and thats why larger diameter and more weight is a real problem.

 

Handling wise those, 16x7s with say 13 lbs each wouldn't worsen my performance over something like 15x7s would it?

 

I went from 195-55-15"s that weighed 15 lbs. each and were mounted on 7" wheels that weigh 9.5 lbs. to 205-50-16" that weigh 22lbs on 6 1/2" wheels that weigh 12.8 lbs. Even with a supercharged engine the heavier wheels are killing acceleration and fuel mileage except on the highway... I'll be putting my old wheels mounted with a new set of lighter weight tires this coming summer... I'll have to use high performance tires so they will not be as light as the 15lb Conti Pro Contact touring tires I had before.... What Mahout says about wheel and tire weight is correct.. If you go as light as you can find you will be amazed at how much better your car will accelerate, stop, steer and ride..

 

If the 15x7s weighed 25 pounds there would be a difference but likely the 15x7's of the came make and style wheel will weigh slightly less. However, there is a good chance the 205/45x16 tires will weigh less than 205/50x15 tires and thats a gain in performance and handling. Remember that the heavier tire requires more effort to rotate as well as turn so the engine is helped by less weight tires and the steering is easier and quicker when the weight of the tire is less too.