I've had it up to 5700 going down a hill on my first tow. The truck kept downshifting when I'd put the brakes on. I feel kinda stupid about it now, but it wasn't funny at the time. Got er figured out now though and love the truck. Just got home a couple hours ago from a 250 mile camping trip with the travel trailer. Came through some heavy winds and the truck/trailer was just rock solid with the equal-I-zer hitch.