New 5er owner!

With or without "Timbrens" the truck will settle (squat) some with a decent load on but all trucks headlights are set at the factory at legal height empty. A 3500HD should have over load leaves to compensate for the increased load on the truck but is still going to settle as load is increased. Timbrens although cheap and effective are basically a larger hollow axle stop which limits the travel of the axle transferring the spring flex to the sidewalls of the tires which increases sidewall heat. Auxiliary air springs and added overload leaves increase the weight carrying capacity of the spring set but don't limit the overall travel of the drive axle. As manufacturers are constantly increasing truck load capacities along with ride comfort the spring main leaves have been made longer and use a progressive spring rate design. However #1 task when buying a trailer is level the unattached trailer so as the frame is parallel to the road surface which means there will be the same weight exactly on both axles and 4 tires with the equalizer square to the frame as well. Measure from the road surface to the bottom of the kingpin plate and this is your proper towing height for the trailer. Your truck 5th wheel height should match this with the truck loaded also being level and square to the road. This is your ultimate towing heights for both units giving you good steering and handling which is where your headlights should be aimed. Auxiliary air springs with the overloads deleted is the only system other than true air ride that accomplishes it all. Ride quality, ride height, front axle loading, good steering and headlight aim. The only reason air springs require air when the truck is not loaded is to prevent the air spring from collapsing inward with the axle extended, too many people leave too much air in them empty making the HD truck ride rough empty.