TPMS for load sensing

Maninthesea · March 9, 2023

I happened to notice my tire pressure was up after dropping a 1,882# pallet in the back. I was not sure how much it rose but it got me wondering, would we be able to get a rough estimate of how much load is put in the bed by checking tire pressures before and after on some known weights then in the future using pressure rise to work backwards to estimate load weight? Would have to work the data up on your own truck since tire footprint and I m guessing volume and stretchability would be pretty tire specific and may drift a little as tires are worn down. I am thinking about puttin a notepad in the truck to start recording data points.

jim

Another JR · March 9, 2023

I think a far better method for crude load estimation is to get to know how much the rear suspension compresses at given weights.

Maninthesea · March 10, 2023

Might be better for some but is a more subjective method. I am thinking numbers while more work might be more objective.

Another JR · March 10, 2023

I was thinking in terms of an objective measure of compression, like how close you are to the overload springs or how close you are to the stop bumpers. Our eyes are pretty good at estimating measurements in the 0 to 6 inch range, and especially good in the 0 to 3 inch range.

I have not had enough loading experience with my new truck to be there yet, but on my old K2500 truck I could certainly tell you within 500 lbs how much was in the bed by looking at how far the axle was from the bumpers based on knowing the weights from weighed dump runs.

I just think tire pressure won’t get you close because the pressure change isn’t that great. The TPMS only displays whole numbers, is slow, and has hysteresis built in. In addition, most of the weight change is handled by deformation of the tire and increase in the footprint rather than straight pressure rise as if the tire was like a piston in a cylinder. If you could measure the footprint and the pressure change you’d get closer, but even then the footprint pressure on the ground isn’t uniform.

I think we are close to seeing real time load displays in new truck, but they will be based on sensors associated with the suspension system and not the tires for good reason. In the meantime, I still think measuring or eyeballing suspension compression is going to be more accurate than trying to use TPMS. Nothing wrong with looking at it and seeing if you can make it work for you, though.

Maninthesea · March 11, 2023

Might be better for some but is a more subjective method. I am thinking numbers while more work might be more objective.

Maninthesea · March 11, 2023

I had not considered objective measuring of bump stop…….
yes TPMs would not be linier due to footprint and defiantly would have to be on hard surface vs dirt or gravel

I will play around with it for entertainment. I figure to add all four tires for a total even though most change will be in the rear.

I think ford has a system measuring suspension and indicating in the taillights. But is more of % of capacity vs #.

on my 2001 f250 I had a good idea by how she rode but it was mostly guessing.

Edited March 11, 2023 by Maninthesea