Noise-reduction wheels? Wheels that actually make a car quieter? Lexus engineers worked hard, no doubt, to make wheels for the 2013 Lexus LS-series lightweight and for all the usual reasons. Lighter wheels don’t take as much energy to start turning, and that gives the LS better acceleration and fuel economy. And lighter wheels, because of their reduced mass, don’t bounce as hard, yielding a smoother ride. But quieter?
Yes, according to Lexus. To make the wheels lighter without sacrificing strength, certain Lexus LS 18-inch and 19-inch wheels have hollow outer rims, a hollow ring just under the “bead” of the tire, where the tire sits on the rim of the tire.
This hollow ring is vented to the interior of the wheel, so it’s pressurized, just like the inside of the tire. The vents, however, are tiny, small enough that air doesn’t flow through them easily.
When the air inside the tire is compressed and released by bumps in the pavement, vibrations are set up and sensed as sound. Bumps in the road and the tire are therefore actually creating noise.
With the noise-reduction wheel, the generated sound waves reach the “resonator hole”—the hole between the hollow ring and the inner wheel—and resonate within the air in the hollow structure.
This causes friction in the air and that friction creates heat. In converting the sound waves to heat, the “air column resonance” is suppressed. And less vibration means less noise.
Voila, noise-reduction wheels.