Dan, I've got to jump in with Shane. Air bags do only one thing - they raise the rear end of the tow vehicle to alleviate squat. But squat is only a
symptom of a problem, and if you solve squat, you haven't solved the problem.
As you point out, the vehicle manufacturer knows what his vehicle can handle, and tongue weight is one of the specs that must be honored. The spec usually comes from the component capability of the vehicle's rear suspension - wheel bearings, shocks, wheels, etc. Air bags and helper springs don't change the capability of any of those. But as the name implies, a "weight distributing hitch" distributes some of the hitch weight away from the rear suspension, and forward onto the front axle of the vehicle and rearward onto the TM axle. Depending on the specific hitch and its adjustment, a couple hundred pounds can be removed from the hitch and placed on those other locations. When that happens, the front of the tow vehicle is more heavily loaded, so it sinks a bit on its suspension. And the rear end of the tow vehicle is able to rise a bit because of the reduced load. The effect is to bring the tow vehicle back toward level. AS A SIDE EFFECT, this reduces squat. But the primary effect is to reduce the hitch weight carried by the rear suspension.
Ads for helper springs or air bags promise to reduce squat, and they do that. Don't misinterpret those ads. They don't reduce rear suspension load, which is the real goal. Weight distributing hitches are more expensive than air bags for a reason. They are more complex (though much easier to install) than bags or springs.
You might take a look at the tutorials on the subject in the TM Technical Library at
https://www.trailmanorowners.com/for...ead.php?t=2616
https://www.trailmanorowners.com/for...ead.php?t=2922
https://www.trailmanorowners.com/for...ad.php?t=21037
Or search the internet for articles on "how weight distributing hitches work", rather than "eliminating tow vehicle squat".
As I noted in my first post, some vehicles can't use a WDH, often for reasons related to lack of a real frame. If your vehicle can't use a WDH, that's unfortunate, since there is no other realistic way to reduce the trailer's tongue weight. But that is not the real issue that a WDH addresses, so please don't mis-state the function of a WDH. You must obey the mfr's specs including the actual tongue weight - even if you use bags to cure squat.
Respectfully submitted
Bill
Linear Mode
