2wd vs 4wd problem

[db2003]

my 2003 xlt has a "thumping" feel and sound, when i let off the gas or driving on flat ground. as soon as i hit the 4x4 high button, it rides as smooth as it ever has. whats going on?

 

[db2003]

ok, so i figured it out. i put new tires on the back and it stopped. i got to thinking, and the day it started, i put my spare on due to flat tire. i guess the tires were all off by lil bit, and it was messing with the auto 4x4.

 

[BigRondo]

ok, so i figured it out. i put new tires on the back and it stopped. i got to thinking, and the day it started, i put my spare on due to flat tire. i guess the tires were all off by lil bit, and it was messing with the auto 4x4.

That's what will happen. Be very careful with the tires on the auto 4x4!