I am running Toyo Open Country MTs in 37x13.50x22 on my 2004 2500. The wheels I have are Pro Comp 6089 8 lug chrome wheels and each has a rating of 3420 lbs. The tires are E rated and also have a 3420 lb rating. I have towed a 10,000 lb loaded enclosed car hauler numerous times with this setup as well as a 6,000 lb boat every weekend during the summer and have never had any problems. As long as your buddy's wheels are rated for a decent load capacity and the tires you get are at least D, preferably E, rated then you will be fine.