Hi everyone,
Im completely new here and this is my first Lexus, coming from Audi and BMW.
Its a great SUV.

i have a 2014 RX, which is still under warrantee with 35k on the clock.
I bought the SUV knowing i wanted to upgrade the look to the F-sport.....
so, I did body wise and bought a set of wheels too.

heres my issue:
on stock wheels 17s when accelerating from a stop, its smooth as butter. but upon throwing the new F-sport 19s on.. when i go to accelerate, it feels as if i have a bowling ball in my trunk.. its a "thud" noise. totally weird, i deemed it fixable by the dealer and took it in.

I did, they swapped out a NEW rear diff. for me thinking it was going to fix it. sure enough.... it didnt. they let my keep the new diff and said we cant help you. I swapped lug nuts, studs, made sure it was hub-centric wheels, even went to verify if the wheels we reps or not.

so to go further in depth, i swapped out just the fronts, its a more faint thud, but with all 4 its more audible and feels worse.
heres where i am at, id put them on and dont mind the thud noise if i know its not hurting the car.

for piece of mind, does anyone know if the F-sport diff or drive shaft is different / suspension is different from the standard? IDK im outta ideas guys.

 

I get a thump(rear) when I first start the car and go in reverse a bit then put it in gear, start to go foward, I sometimes get a little thump. This is the only time it happens or that I notice it. No. nothing is rolling around. It is a 12 with 43000 miles still under warranty but I haven't taken it in to the dealers yet,