16 trd off road tire chop

hi guys i have not posted in a while very busy year at work. my wifes truck is at 18,000+ miles all service has been done to this point. tires have been rotated 2 or 3 times i think, they have been kept at 30 psi,and have quite a bit of chop to them (you know the sound) is this normal,any others with this problem?. are these good years known for this?. i'm trying to figure this out,i would not think i would need a alignment,this truck has not been off road yet unless you count some dirt roads offroading. if you guys can give me some advice and or tips it would be a big help. do you think i can bitch to the dealer and get them to do some servicing for free.i hate to say it but as much as i like this truck its kind of a lode of dung. thanks for the help

 

Pics ??? Don't know what "tire chop" is. I run my tires at 36PSI...