YODAONE

Our LS400'S have only two mounting holes to affix the rear license plate...so the plate tends to flop around or rattle when underway and during trunk opening and closing.

Never mind that a raw Aluminum license plate backing is rubbing and reacting with the paint and stainless steel or metal fasteners....

A simple solution is to use rubber isolating/ damping grommets from E-A--R.

The EAR grommet kit.
Inserted grommet into all four holes of license plate. Bottom hole depicting the grommet inserted through plate and frame which secures them tightly together. Backside depicted.
And opposite side showing grommet through license plate face and frame.
Much quieter.
Aluminum license plate does not rest on trunk face

RA40

iTrader: (6)

Good post!
I've been using the 3M version of these round vinyl bumper dots similar to these:

Home Depot, Lowes, Ace Hardware sell similar too. Really bugs be to hear a rattling license plate.

UNCNOR

iTrader: (1)

Mine are from Ace Hardware: Danco 00 flat washer. stock number 35062B.Good luck.

valex

I have a double sided tape on bottom edge of back side of license plate. Works for me, doesn't rattle.

timmy0tool

iTrader: (7)

my plate has a slight bow on it so it pushes against the trunk so there are no rattles, but this is a great idea to isolate it completely so no paint is scuffed off!