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

My new wheels are DOT, they are thick aluminum, maybe an inch thick in the center? At 15x10 they are lighter than the 14x5 or what ever the factory steel wheel was.

JEGS 69134: SSR Mag Wheel 15 x 10" | JEGS

Jegs lists the shipping weight as 21 LBS I'd bet at least 3 or4 LBS of that is cardboard.