ls110
John
I would guess your trunk lid is absorbing a fair amount of downforce that is not being transfer to the tires. My lid had significant reinforcement and found the more I reinforced, the more I was getting deformation of the lid. Not surprising when you consider the 500 pounds of downforce supposedly gained at 125mph. Just this winter I am now bypassing the lid and supporting to the frame. And shaved some pounds doing itI do not have additional reinforcement bracing the trunk, although I do have the 302S hard trunk stoppers.
It would not be a bad idea to have additional trunk reinforcement--that cannot hurt you.