With my LR3, I towed a 5,000 lb boat setup over 10,000 miles with zero issues. It had a very heavy tongue weight, I estimate at 500 lbs+. With my LR4, I'll be towing a 6,500 lb Jeep and trailer across the Rockies from Minneapolis to Moab (1,200 miles?) and I'll report back in to let you know...