I replaced my 1/2 worn OEM tires and wheels with wider tires (205/55-15) on '88 RX7 convertible BBS wheels and lost 4 pounds per corner - BIG difference in the way the car rides and handles.
My Miata wheels/tires weigh 102 pounds for the set of 4 - The OEM P5 wheels/tires were 140 pounds for the set of 4 (35 pounds each, but as I said, 1/2 worn) My new setup was 124 pounds brand new - Still not "super light" but a dramatic improvement