with RV tire expert Roger Marble
I received this question and thought that others may have a similar problem.
Hi. I have followed your postings on this forum and I own a 2017 Newmar Ventana 4002. I am trying to understand and resolve an issue with my coach where I have a 1000 lb. difference in weight on the front axle side to side. I have had the coach weighed on all 4 corners 3 times and get the same results. My understanding, and I think it may have been in one of your posts, is that the difference should never be more than 500 lbs. side to side.
I am having a conversation with Newmar about this and pushing them for answers why, as I am well under the GAVR and well under the GVWR. I have unloaded and moved the contents in the basement and inside the coach around hoping to make a difference and the reality is I don’t have much to move.
I am looking for any studies or evidence that I can show Newmar that this is not safe if indeed my information is correct that side to side should not be more than 500 lbs. I am hoping you might know of something I can get my hands on or someone I can talk to.
Thank you for taking the time to read this PM.
Sincerely, Newmar owner
You may have misunderstood the side-to-side weight comments.
It is suggested that people get “4 corner” weights rather than just axle weights, as it is known that some coaches are unbalanced side to side.
We do this because if you only get axle weights and simply divide by 2 and assume your side-to-side weights are even, you could end up with an overloaded or underinflated tire if the sides are not close to even.
Not sure where the 500# figure comes from other than looking at the load increments in the tables for each 5 psi. You will see that with some large tires the load capacity can increase by a few hundred pounds with an increase of 5 psi.
I do not remember ever seeing a “should” not be more than 500# difference statement.
You have confirmed that your coach is not balanced side to side and it appears you have made a good effort to get more balanced but have not been able to because of the design/layout of your coach.
With that in mind, and knowing the load on the “heavy end,” you need to consult the Load/Inflation tables and use the heavy-end weight to learn your minimum inflation for all of the tires on that axle. I still recommend you add 10% to the table inflation number as long as you do not exceed the max inflation rating for the wheels. This 10% helps avoid TPM (tire pressure monitor) low-pressure warnings due to an occasional drop in ambient air temperature.
I trust you have confirmed with your RV manufacturer that the wheels are capable of supporting the heavy-end load.
I hope this clarifies what you need to do and answers the question of “why” we suggest you get the weights on each end of each axle.