"Unsprung mass" refers to the weight of the parts of a vehicle that are not supported by the suspension system, such as the wheels, tires, and brakes. Essentially, it is the weight that directly touches the road surface. Full definition
Reducing unsprung mass in the wheels and brakes make the all - new BMW 6 Series Gran Turismo even more agile. (press.bmwgroup.com)
The adoption of standard 19 - inch forged aluminum wheels with 255/45 front and 285/40 rear profile tires is said to bring a reduction in unsprung mass in comparison to the older CL63 AMG. (autoweek.com)
Overall, some 17.6 pounds have been pared from the standard 3 - and 4 - series suspension — 11 pounds up front, and a further 6.6 at the rear, leading to lower unsprung masses at each wheel. (autoweek.com)