If you take 5kg off pr wheel, then it will eaquel to about 80kg inside the car ca.
unofficial you say 5kg x 4 = 20kg x 4 = 80kg inside the car.
2,5kg x 4 = 10kg x 4 = 40kg inside car etc etc
I got this from an ex F1 driver (old friend) , dont know how much you can use this off course, but seems right.
It“s rotating mass so better for acc and breaking