Weight Distribution in MH with Tag Axle

[AlGriefer]

OK, here's a question for the experts!  ???

When you check the weight distribution on a motorcoach with a tag axle, you can vary the weight on each axle by changing the air pressure on the tag.

As an example, my MH has a capacity of 15, 160 on the front axle, 23,000 on the dual drive axle, and 10, 000 on the tag.  My coach, fully loaded weighs about 43, 000 and I can change the load on the front axle almost 1,500 lbs without exceeding the limit on any axle.

So the question is...

How much weight should I put on the front axle and how does this affect the steering?  :

Al

 

[Gary RV_Wizard]

Interesting question, Al.

The first thing that comes to mind is that the tire pressure in the fronts should be changed to match the increased (or decreased) load.  Unless of course you run the tires at max axle capacity all the time.

Theoretically there should be no effect on steering as long as the tire pressures are correct for the axle weight, but I doubt if that's true in practice. For one thing, the alignment was probably done at some specific weight and it's common for the front end geometry to change a bit as the weight changes and the suspension shifts to handle the load.  Therefore I would choose a weight distribution, align the front end for it and then try to maintain that same weight up front as much as possible.

The other thought is that more weight on a tire generally increases wear slightly, so [all other things being equal] I would opt for lighter rather than heavier front end loads. But even that has to remain within reason, so a really light front end tends to get "squirrelly". There is probably some minimal percentage of total weight that ought to be on a  front end, but I've never seen a rule of thumb number and there probably is no such number that works across multiple front suspension designs and vehicle weights.

These are the only factors I can think of...

 

[AlGriefer]

Interesting question, Al.

The first thing that comes to mind is that the tire pressure in the fronts should be changed to match the increased (or decreased) load.  Unless of course you run the tires at max axle capacity all the time.

Theoretically there should be no effect on steering as long as the tire pressures are correct for the axle weight, but I doubt if that's true in practice. For one thing, the alignment was probably done at some specific weight and it's common for the front end geometry to change a bit as the weight changes and the suspension shifts to handle the load.  Therefore I would choose a weight distribution, align the front end for it and then try to maintain that same weight up front as much as possible.

The other thought is that more weight on a tire generally increases wear slightly, so [all other things being equal] I would opt for lighter rather than heavier front end loads. But even that has to remain within reason, so a really light front end tends to get "squirrelly". There is probably some minimal percentage of total weight that ought to be on a  front end, but I've never seen a rule of thumb number and there probably is no such number that works across multiple front suspension designs and vehicle weights.

These are the only factors I can think of...

Gary,

Very similar thoughts to what I've had.  Certainly the tire pressure has to be correct for the load and equal on both sides.  It may be that the difference in weight possible by adjusting the tag is not enought to make a difference.

Al