Trailer Porpoising

[Groover]

Originally Posted by Cumminsfan

If thats the case then I would live with it. The majority of the time you're on the hwy/freeway.

True but I've found the problem appears at highway speeds on concrete surfaces.

[Ray,IN]

Originally Posted by Groover

Thanks @CecilD ! I was just thinking about that and saw your post!

Here is the chart:

https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

I have 6,400lb on the axles, that is 1,600lb per tire. Looking at the chart 30 PSI is 1920lb, so plenty of room. Hmmmm... very good idea!

So today I drove 500 miles. The faster I go the less a problem it is. At 65 MPH there is no issue at all when going over rough patches of road or bridge joints. However 10 MPH in a gravel gas station I can feel it.

Not a good idea; tandem axle trailer tires are subjected to great sidewall stress when making sharp turns, low inflation compounds the sidewall stress.


My thoughts;
1. if your tow vehicle has P-rated(passenger car) tires, switch to LT tires(light truck); they have much stiffer sidewalls to reduce tire "squirm" under load.
2. Readjust your WDH, this is the most accurate and complete how to properly adjust a WDH I've ever seen in my 40+ years of RVing.
3. I recommend reverting to your old spring rate, your new springs have such a high rate the suspension cannot perform correctly.


A side note; I had heavier axles put under our 40' 5er years ago, against the advice of the shop foreman. It wound up causing the 5er aluminum sidewall structure to break at critical points by transmitting uneven road surfaces to the superstructure instead of absorbing the jolts and vibrations.

[Jay D.]

Originally Posted by Ray,IN

Not a good idea; tandem axle trailer tires are subjected to great sidewall stress when making sharp turns, low inflation compounds the sidewall stress.


My thoughts;
1. if your tow vehicle has P-rated(passenger car) tires, switch to LT tires(light truck); they have much stiffer sidewalls to reduce tire "squirm" under load.
2. Readjust your WDH, this is the most accurate and complete how to properly adjust a WDH I've ever seen in my 40+ years of RVing.
3. I recommend reverting to your old spring rate, your new springs have such a high rate the suspension cannot perform correctly.


A side note; I had heavier axles put under our 40' 5er years ago, against the advice of the shop foreman. It wound up causing the 5er aluminum sidewall structure to break at critical points by transmitting uneven road surfaces to the superstructure instead of absorbing the jolts and vibrations.

THIS ^^^^^^^
Jay D.

[Tunaman1]

I’m willing to bet @30 p.s.i. Trailer tire pressure they will run hot and guarantee you will have blow outs.