Counterpoint.
If it's a lightweight car with heavy wheels, it can work out to 2%. (my car - 2500 lb, lose 6 lb per wheel) That's in the same ballpark as power increases claimed from air intakes or exhaust mods,
BUT it also benefits ride quality, handling and braking.
You can also move to a smaller diameter wheel. That will improve rotational inertia even more, along with usually being lighter due to the smaller size.
This is an upgrade I'm considering, downsize from my heavy 16" alloys to a 15" sport wheel. Stock rims are 17 lb each, Konig Helium 15" are 11 lb and cost under $100 each. I'd love a set of TE37's but the price...
