Reducing the wheel mass does not only mean reducing the vehicle total mass: it mainly means reducing the unsprung mass. Lower weight of the unsprung mass ensures better tyre grip on the road surface.
If we consider that inertia is the tendency of a body to keep its equilibrium of rest or motion, the following conclusions ensue:
LOWER UNSPRUNG MASS = LESS INERTIA =
• better response of shock absorbers, improved comfort, higher driving pleasure
• better rotation inertia, hence improved performance in acceleration and braking
• improved global vehicle performance
• reduced fuel consumption.