Recently I bought a set of 14" fiero wheels, very light when compared to the GT wheels. Just got my winter tires mounted yokahama gaurd X, size is 185/70. they look pretty bad on a GT but the bite the snow like crazy.

Anyways they have to be like 10 pounds lighter then my GT wheels with 225/50 tires and the difference is incredable even with a little larger circumfrence and a way small contact patch the weight difference makes the car move noticeably faster when accelerating at any speed. car stops easier to.
cant say the handeling improved though... oh well it is winter and i dont feel like im gonna die on snow anymore.

My point... light weight tires and wheels RULE.

..but are a ***** to balance....

You noticed the reduction in the reciprocating weight of your power train, which uses up fewer horsepower than a heavier reciprocating weight. Your engine has to overcome the reciprocating inertia before if can start to propel your car. That uses up horsepower and slows acceleration. This is the kind of performance gain you would notice with an aluminum flywheel if you have a manual transmission.

the latest sport compact car mag. has this as it's cover story.