Tried a quick search- no luck: Does weight of wheels really make much of a difference?

To keep it simple. Think of the tire/wheel assembly as a flywheel. How do you think the weight of a flywheel affects acceleration and deceleration. Think..for acceleration you would want a light flywheel, it will rev quicker using less power. Think..climbing a hill, a heavy flywheels momentum causes the car to want to keep going. One of the first things that someone who puts larger tires and wheels on his 4x4, suv etc...has to do for safety is to install bigger brakes to stop it. Why ??