My tailgate doesn't rattle-
I adjusted the tailgate alignment ramp (below the latch) and did this-
First, as said the 35" tire is just TOO BIG/HEAVY for your stock tailgate-
Second, my little 5/8" carriage bolt is like a rubber bumpstop, except it eliminates abrupt "downforce" that the spare experiences from bumps/potholes/ledge drops-etc-
The tire slides over the round bolt end and it provides an "upforce" to the tire--simple/effective-
It has worked for over 4 years/w no rattle or hinge trauma !
You also have to have effective bumpstops on the tailgate also-