Volt Z saw the positive change becaue he lowered the unsprung weight of the vehicle.
Unsprung weight is anything that isn't supported by the shocks and springs. Lighter brake calipers and suspension pieces can help improve the handling a car. The spring and shock are trying to press them down. With a lower inertia because of the reduced mass makes it easier to control. think if as catching a ping pong ball and a golf ball both traveling at the same speed. WHen it hits your hand the golf ball is going to make your hand move more and be harder to stop even though they are of similar size and speed.
Reducing rotating mass pays big dividends. The spinning wheels work like gyoscopes so turning them because more difficult as they gain speed. The extra inertia from a heavier wheel makes if harder to start moving, change direction, and to slow. Interia isthe tendency of a body to preserve its state of rest or uniform motion unless acted upon by an external force. the more mass it has the more external force is required.
It would make sense that if VolkZ bought a set of 18in rims of the same style as his 19's the 18's would be lighter and he would gained even better results. You also have to take in to acount the extra weight of the tires. To maintain the same tire diameter or rotational circumfrence(sp) an 18in tire is going to have 1 more inch of rubber on both sides off setting the weight reduction of the smaller rims. light brake disks also have the same effect. This is the reason for racing cross drilled rotors.
Lighter unstrung weight has a huge effect on motorcycles. This is why people pay $4000 set for CF rims that save them 4lbs. Since bikes don't have a built in camber setting , it is easier to tilt the wheel makes for a much more responsive ride.
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