More tire on ground is more resistance which is more fuel. You should be able to find vx or hx wheels for 200$ 300$. They are 9 and 10 lbs. You could get some volks. They are 7 lbs. But 2000$. Where are you located.
I disagree about rotational mass. It should not make a meaningful difference for anyone who drives reasonably efficiently. A stoplight-racer might get an effect from a severe difference, but a gas saver who's talking about only a few pounds? Don't think so.