How many miles are on his truck?
I agree with the others in that it sounds like too many short trips and not getting it nice and hot. My truck is primarily used for towing our 16k fiver and I have not had any issues related to the emissions system as of yet.
The transmission problem is definitely not common with the HD Ram and tires are indeed a wear item (my truck needs them too).
Personally, after owning 3 diesels with my current truck being my favorite there is absolutely no way I would go back to gas for towing heavy.
