Just as a reference treaded race tires are around 6KG in a 185/60 13, add that with a 4KG wheel and you could indeed save 24KG total. Also the best way to think of unsprung weight is if you get tackled by 61KG "heavyweight" like me vs some 120KG guy named tiny..............keeping control of tiny is a lot more work. It's the sprung to unsprung weight ratio, an old Dodge Polara with a 50lb wheel rides so wheel over bumps because the car is 80 times heavier than the wheel. In contrast the 1200 is only 50 times the wheel weight so it's easier for the wheel to move the car.

Now as for wheels.............if you think of them like flywheels that needed to be speed up and slowed down it quickly becomes obvious why lighter wheels are what you want. Also rolling resistance is a big deal my old 125 Roadrace bike used a tiny 90/90-18 and when I raced a Miata in Showroom Stock I used a 10mm narrower tire for qualifying because it was worth 2 tenths, over the course of a 12 lap race they'd start sliding around two much and the time made up on the opening laps would be lost on the closing laps.

Finally on a 1200 with stock A Series, 12KG is equal to about 1 HP power to weight wise....................the cost of getting 100KG out of the car would be far more than simple installing a different camshaft and Weber DGV Carb or a GX set up. So over all weight isn't as big a deal as we often make it but yea you want to keep the wheel weight down. Oh if it's any consolation I've taken more than 50KG out of my car only to have the roll cage make it all back up.

Tom