Leveling with air bags correctly

[ajriding]

After reading forums I did what they said. I think all that I have read have been COMPLETELY wrong.
I don't mean to offend anyone, and I'm sure maybe this was mentioned already buried in long strings….

Your truck is meant to be loaded, and this is why the rear sits high when the bed is empty.

When you load your truck the rear (rear bumper) will drop lower, BUT ALSO the front will drop lower too since some of the weight is on the front also.

Some folks are all saying measure your rear bumper off the ground when unloaded and then to inflate the air bags so the height is back to that original measurement after you load the camper.

THIS IS SO WRONG.
DO NOT USE THIS METHOD.

This method actually made my front end caster out of whack and I was getting uneven tire wear.

As mentioned, the front of the truck most certainly sagged down from the weight of the truck camper, so lifting the rear back to the original measurement was not only wrong, but exacerbated the problem because the front had sagged a little so the truck angle was even more pointed down than it was unloaded.

First measure both the front and the rear to get a difference between the two.
Example, the front is 15 inches and the rear is 17. The difference between the two is 2. Don't worry about the total distance from the ground anymore, just this difference.

When you air back up you will be looking for a front to rear difference of 2. Your ground distance may or may not be the original 15 and 17, this is fine since there is weight on the truck - reason being that the front is lower. It could be 13 and 15 now instead of 15 and 17.
On top of this you may want the truck rear to sag a little bit since this is how the truck is intended to be when loaded. The manufacturer intended the truck to sit lower when loaded than when unloaded, how much I do not know.
Maybe the truck is not meant to sit at the same angle when loaded as it is when empty.

On mine if I have a 2 inch front to rear difference then when loaded I will make it a 1 inch difference instead.
There is no science to this, it is just a guess and I am sure well within parameters of the truck.

Side note: on TCs you should use the air bags that sit under the frame (on top of the leaf springs or inside the coil springs) and never the ones that sit/mount inside the frame rails. Adding spring support inside (closer to center) will make it more unstable since you are supporting the load closer to the center than it is when loaded on the stock springs.
The "inside the frame rails" bags typically use the bump stops as mounts. These are fine and dandy for towing where the extra weight is a trailer placed on a ball hitch in the center of the truck, but not for tall heavy loads in the bed.

[mountainkowboy]

jimh425 wrote:
No, you don’t have to settle for having too much metal spring and rough ride unloaded to have a more level ride loaded.

My truck rides fine unloaded or at GVW, for a 1 ton dually. I didn't have to add anything to it to run a 4,500lb TC. My factory suspension works just how it was designed....no bandaids needed, and bags would have no effect on my ride loaded or empty.

On the other hand my 95 F350 that had bags, to compensate for the sag, rode like sht and was "tippy" till I upgraded the suspension. Then it rode fine.

[ajriding]

My eyes rolled back in my head for the anti-air-bag post. Lol, those guys either never had air bags or had them on incorrectly, like guys who mount them inside the frame rails…. Air bags are wonderful.

My trip was across i-40. Normal straight roads. No mountains to speak of, and the interstate mtns are straight. There is no cause from the road or driving that would have cause the tires to wear.

Regardless of cause or theory, the lesson is that truck are meant to be loaded, so the advice telling to raise the truck back to unloaded height with the TC on is the wrong advice.
Let the rear settle a little as it is designed to do. Not too much of course.
Do not use air bags to try to lift back up to the unloaded height, and if you are going to measure then measure the front also since all 4 springs will have added weight to them. Lift it back so the truck sits level.

[jimh406]

No, you don’t have to settle for having too much metal spring and rough ride unloaded to have a more level ride loaded.

It sounds like a couple of experts on truck air bags, aren’t. Go figure. :D. Of course, air bags on pickups are very similar to large trucks. The same companies make the bags for several different load levels. BTW, Air Lift also describes their bags as spring and suspension. They can either exist as part of the suspension or replace springs on a suspension.

It’s ok though. Feel free to use only metal springs if that works for you.

From Firestone ... notice the word “spring”.

Air springs, also called air bags or air helper springs, offer many benefits. One, they help protect cargo by preventing unbalanced loads and bottoming out, while eliminating sag. Air springs also help improve your ride safety by enhancing steering control and braking, keeping headlights level and preserving tire tread. With Ride-Rite Air Springs, you can chase after new adventures with confidence.

I could pull even more text from Firestone and Air Lift, but it’s obvious, they do what they are made to do. As I said, it’s fine if you don’t want to use them. But they serve a real purpose even if you don’t personally like them.

You can also use them wrong like many people do to try to make their truck a completely different beast by running very high pressure. Just bolting on extra heavy springs can also be a bad solution.

[mountainkowboy]

twodownzero wrote:

mountainkowboy wrote:
bags are a bandaid for not enough suspension

Like almost every semi on the road? Bags are suspension!

Apples and Oranges....the bags on semi's are NOTHING like the bandaids that you're touting. The "bags" do nothing but unload the suspension on the truck, they are NOT an addition to the suspension. If you have to use airbags to level your truck your present suspension is overloaded.....PERIOD, and no amount of add-ons other than more spring will cure the ills of it. I've used both suspension and airbags to make a truck "handle" a camper that was clearly more than the truck was designed to handle, and suspension wins EVERY time. Red is "maxed out" with the S&S and still sits 1.5 inches higher in the rear as it was designed to handle that weight and doesn't need "bags" to fix it's deficiencies.

[Bedlam]

twodownzero wrote:

mountainkowboy wrote:
bags are a bandaid for not enough suspension

Like almost every semi on the road? Bags are suspension!

Those semi bags are nothing like what the add-on bags are like on a pickup. That's like comparing a 5-lug rim to the 10-lug on my truck and trying to say they are the same. I don't know how you can equate them unless you are not knowledgeable about the differences.

[Grit_dog]

twodownzero wrote:

mountainkowboy wrote:
bags are a bandaid for not enough suspension

Like almost every semi on the road? Bags are suspension!

You need to pick which side of the fence you’re on.
Weight cop or realist?

[twodownzero]

mountainkowboy wrote:
bags are a bandaid for not enough suspension

Like almost every semi on the road? Bags are suspension!

[jimh406]

mountainkowboy wrote:
bags are a bandaid for not enough suspension

Uh, no. There are a number of reasons to use air bags.

[mountainkowboy]

bags are a bandaid for not enough suspension

[Grit_dog]

Example same 07 Dodge solid axle truck, 170 k miles now and onky one alignment, toe was off and pulling one direction. Hit something I suppose. Original steering components.
Tire wear was probably 2x as much living in CO mountains commuting I 70 or Hwy 285 down into Denver daily compared to other locations where driving habits are differnet.
Something to think about. Did you notice tires feathering after touring through the mountains back n forth, lots of switchbacks, for a while then it corrected itself after driving back home on "straighter" roads?
Did you notice any feathering or wear on the outside of rear tires?

Just throwing out some ideas as to the cause. Becasue a few inches in rear ride height doesn't compute as the cause.
I have had work trucks and personal trucks, 30 or 40 of them over the last 25 years. Some are loaded all the time and perpetually "sagging" a bit others not. Mountains, flatlands well over 500k miles and the accelerated wear your describing happened all the time but exclusively when living in the mountains where no matter which direction you drove it was high speed curves or switchback roads all day everyday.

The fact that the tire wear stopped leads me to believe it was more the driving/road conditions that cause the wear than how the truck was setup.

Thinking about your trip, MI to west coast and back. First 1000mi is straight roads, then a bunch of mountains and then more mountains depending where you went, then 1000miles of stringy road home. Possibility the mountains in the middle of the trip are the culprit?

[Grit_dog]

^ This does seem perplexing since you said the tread feathering stopped when you adjusted to "loaded" rear susp height or level vs unloaded rear height.
1. Becasue your truck was aligned presumably at "unloaded" rear height.
2. Becasue it shouldn't make one bit of difference especially on a solid axle truck.
3. Because it never felt out of alignment. Yet the tire wear changed.

I presume the steering components are/were healthy. No excessive play in ball joints/tie rods.
Having lived in the mountains and in places with straighter roads, Mountian driving absolutely chews up tires quicker and the effect was/is outside tread feathering.
Living in CO mountains with daily commutes on winding highways, multiple trucks, both IFS and solid axle, I'd rotate tires pretty regualrly to keep them wearing ok and sometimes flip the tires on the rim to wear the "other half" of the tire out becasue the outside would wear considerably more than the inside. I attribute this to doing 50-70 mph up and down the highway every day with many sweeping and tight curves.
Never seen this type of wear elsewhere.

[ajriding]

Didnt want to get into alignment discussion but since u insist…
99 Ram, 4x4 , extended cab, long bed. air bags of course, stock suspension otherwise. I removed the previous front leveling kit since rear was sagging (this before the air bags) so it is back to stock, then I had the alignment done.Dry camper is listed at 1,900 lbs. Trailer hangs on an extension. Trailer is listed as 700lbs and is loaded tongue heavy probably which easily drops bumper another inch. Trailer is lifted 8 inches so is level with truck/hitch.

(I have WD hitch but am not using it currently on this light of trailer since off-roading was possible and I didnt want to mess with WD for that. I may try it for other reasons on next big trip)

Tires in the front were wearing pretty bad, I think "feathering" is the term for when you see on the outside edge the knobs ramp up creating a sawblade effect. i drove half way across the country before I noticed it was getting so bad.I lowered the rear because was all I could think was the difference since I did not hit anything to mis-align the front end. The wear stopped and the vibration soon quit and the tires wore normally after I lowered the rear. I drove the rest of the way to the ocean, then drove back with no further issues - over 5k miles total.
you are right, this little difference seems like it would not even register for throwing anything out. Could it be weight? I doubt such a small difference would change weight on front end.

At the time I did not consider it could be simply toe-in. As you rotate the rear of the truck higher the toe should get more inward or is it less inward, either way toe slightly changes with angles, but should be so minimal that hardly worth considering EXCEPT that these are expensive tires so everything is worth considering.

Like I said, empty ride height with 2,500 lbs in rear created worn tires, but sagging it a little kepr tires happy. Im interested if anyone has real-life experience on this….

[Grit_dog]

Ok, fair enough.
Still haven’t posted what truck, load etc.
But yes , assume 12’ length wheelbase and 4” of sag in the rear. That changes caster angle about .3 deg. That’s less than the published “in spec” range of caster angles for trucks.
And fwiw, the reccomendation for Rams that yield the most solid steering are greater by more than the caster would change with the camper on than OE spec. In other words there’s publicized cater specs that have a considerably greater deviation than the camper puts on it.
And static toe in doesn’t magically go straight. Just like caster we’re talking very small measurements. The difference between 0.00 toe and recommended toe in specs is pretty minute.
Good conversation though.
Question, what was your criteria for determining tire wear empty vs loaded. How many miles? Did you Rotate tires between loaded and unloaded?
What was your caster angle set to by the shop?

[ajriding]

It's easy to understand actually. Caster was out. This caused tire wear. Caster was not out on truck, it was out because the suspension height was changed which made caster out. Tire wear resulted. Caster can cause tire wear despite forum user's doubts. Caster is an adjustment on vehicle alignment, and caster should be correct and to spec.
Maybe it could have been something else, but caster does change when you raise or lower the rear end, so this is the first suspect. There is no wear on front end parts. If there is something else that changes from a few inches of rear lift enough to cause tire wear I am all ears, and that same something goes away with a few inches of rear lift change…
For those new to caster think of the front wheels on your grocery cart. They are called casters. They run like a backwards bicycle fork, and on a backwards bike fork would always want to run/find straight ahead.
Your truck will be slightly toed in also (and when up to speed somehow this toe migrates to the tires being parallel). I'm not sure if toe combines with wrong caster to make the tires wear or what, someone expert on alignment can explain it, but I doubt ppl are that much interested in details. My initial thought is that as you increase caster angle that toe also increases and this will result in the outside tire wear I was seeing. With the truck loaded with over 2,500 lbs I am sure other alignment angles get skewed so explains the reason I only saw wear with the truck loaded vs not loaded, and the frame at the same angle in each case.
The main point is to keep an eye on tire wear and know that my experience was that when loaded with a TC that the tires/alignment liked the rear of the truck a little lower than the high unloaded rear with no weight.
If you want to disagree that caster matters then instead talk to my alignment guy who I paid $$$ to make sure all alignment specs were correct. Or talk to GM as to why they care about proper caster… (being a little sarcastic there 😉
Caster matters, wrong caster will cause tire wear. If this was my issue or not - to be determined, but it is possibility and fits.