E350/450 Cab-Chassis w/ Composite Box Body
- Thread starter luthj
- Start date
luthj
Engineer In Residence
But where did you source those tables from? (I sincerely hope it wasn't from an AI summary).
I am not arguing against safety margins, but 18% is a very specific and fairly high margin.
The wheel and tire manufacturers load tables for commercial and LT tires already have some safety margin baked in.
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luthj
Engineer In Residence
So you don't have a source, and those are your personal targets. It is totally fine to have personal design goals, but please don't go around telling folks to derate their tires 18% without that caveat. If you got that data from an AI summary, I strongly advise to find some better first sources, ideally industry specs, regulations, etc.
I would also note that "moving weight forward" blindly can cause just as much of a problem. Overloading the front axle worst case. Though less of an issue on a medium duty truck. Much better is to actually measure curb weights, and the CG of the box. Then calculate the adjusted CG for the added weight (engineering vs guessing).
I would also note that "moving weight forward" blindly can cause just as much of a problem. Overloading the front axle worst case. Though less of an issue on a medium duty truck. Much better is to actually measure curb weights, and the CG of the box. Then calculate the adjusted CG for the added weight (engineering vs guessing).
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Seems like you are fine with being overweight on LT tires, not me
luthj
Engineer In Residence
*Citation needed
First off, I never told you my target completed weight. I could be 30% under the tire rating for all you know.
Secondly, you now appear to be claiming that a tires rated load is now "overweight".
There are in fact de-rate factors when using tires in certain applications. P-metric tires for example need to be de-rated by about 10% when used in an LT application. However, I am not aware of any global de-rate factors for LT tires, aside from when used in dually configurations.
Now if you have some extensive experience, or data to backup a global 18% de-rate for LT tires, by all means please post it. You are welcome to have your own opinion on safety, but please label it as such. You don't get to arbitrarily redefine "overweight", at least not without pushback, and especially not when there is published standards for allowable load. This is doubly so when you are posting in someone else's thread providing unsolicited feedback.
For comparison I have seen many LT vehicles with published GAWR which are identical to the tires combined load rating. If a manufacturer is comfortable with that, I see that is good evidence that tire ratings should be taken seriously.
luthj
Engineer In Residence
I didn't go through the entire website. I stopped when I saw "walkable TPO roof". I can almost guarantee this uses a vacuum bonded traditional RV box, with a rubber over plywood roof. While its good to have more options in the space, this appears to just be a slightly modified Elkhart Indiana special. With all the downsides therein.
I personally think, that unless you really need a heavier duty 4x4 system, you are better off going with Transit Ekko vs this unit, as they have a better than average box. Not to mention better driver ergonomics.
The other major downside, is from what I can tell, its just all the same medium to low quality RV appliances. Propane used everywhere (fairly expensive way to heat). For that listed price there isn't any real electrical system from what I can tell on the website.
luthj
Engineer In Residence
For clarity, I am not knocking all the "traditional" RVs out there. They do have a place. But if you plan to own a vehicle long term, I would avoid them, especially if your usage is off pavement more often. Those boxes will eventually develop leaks, after which they pretty rapidly become scrap. Disbonds, rot, etc. Obviously I am guessing about the cabinets in the unit above. However most of them are just MDF, staples, and a barest bit of glue. All with "hardwood" front panels/doors. Heavy, and not very durable. At least with the Ekko and similar the cabinetry is a bit higher quality.
For the about 1.5-2x price increase to build our custom camper which is the subject of this thread, I will end up with unit that has at least double the lifetime. I once renovated a middle tier 5th wheel that was 9 years old, and had about 35k miles on it. Never again. Hidden water damage, dangerous wiring, and sub-par panel structure convinced me otherwise.
For the about 1.5-2x price increase to build our custom camper which is the subject of this thread, I will end up with unit that has at least double the lifetime. I once renovated a middle tier 5th wheel that was 9 years old, and had about 35k miles on it. Never again. Hidden water damage, dangerous wiring, and sub-par panel structure convinced me otherwise.
Budget $120K to $135K
luthj
Engineer In Residence
Budget for what? They don't charge you per word here!
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