Jump to content

TPMS for load sensing

Maninthesea
 Share

Recommended Posts

Maninthesea Enthusiast

Maninthesea

Posted
Posted

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 Senior Enthusiast

Another JR

Posted
Posted

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

  • Like 1
Another JR Senior Enthusiast

Another JR

Posted
Posted

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 Enthusiast

Maninthesea

Posted
  • Author
Posted (edited)

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 by Maninthesea

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.5k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,914
    Total Members
    8,960
    Most Online
    AidenVorpagel
    Newest Member
    AidenVorpagel
    Joined

  • Who's Online   3 Members, 0 Anonymous, 1,283 Guests (See full list)

  • Latest Articles

  • Posts

    • jake111
      Gasser Subforum Has Been Quiet - - So, Regenerative Braking and Using L10

      By jake111 · Posted

      Thanks newdude!  By the time manual selection is needed, I'm probably too much of a control-freak to depend on the transmission sensing braking to activate automatic downshifting.  I would be anticipating the situation and already be manually downshifting.   This truck replaced a 2004.5 LLY diesel with the Allison 5-speed.  Putting it in T/H made noticeable differences (when the torque converter locked, upshift points, downshift behavior).  On this 2024 gasser with the 10L1000 I haven't been able to detect much, if any, difference.  Ok, I can never tell now when the torque converter locks up.  But I also don't notice differences in shifting.  For downhills, I've probably already manually downshifted by then anyway.  Since it's also more awkward (than the 2004.5) to engage/disengage I don't even bother.  Or maybe it doesn't really matter with just a 3k lb. camper in the bed?   Thanks also for the list of reasons the charging system might select various voltages.  However, what I am seeing doesn't fall into any of those categories.  It very definitely, and very consistently, rises after coasting/braking.  Maybe not immediately, but not very long after coasting/braking.  Very consistently drops voltage when no longer coasting/braking.  It might also be interacting with the camper battery charging (I might disconnect the camper and see if it changes the charging behavior).  I also need to recheck turning on headlights for when I want to force it to charge the camper.   Another JR, in June I converted the camper to LiFePO4.  Since it's not a good idea to try to charge lithiums directly using truck, I installed a Victron Orion XS DC-DC charger (which BTW is AMAZING!!).  Being cheap, I only had to buy that one item (besides the battery, of course) to do the conversion.  The camper OEM 120v battery charger (only 19 years old and works perfectly) and the truck feed the input to the DC-DC charger (not at the same time).  But I didn't want the camper charger feeding back to the truck so I kept the old separator.  I considered replacing the separator with a 30amp diode but that means more work and might add another 1/2 volt drop.  One thing that surprised me was the voltage drop over the long 10awg wire run, so I can only charge smoothly at 8 amps (because the DC-DC charger is completely configurable).  Another reason I don't want an added voltage drop with the diode.  I might also be a little lazy but all this work is being done under the sink with a small cabinet opening.    
    • davester
      cam upgrade in CA

      By davester · Posted

      apparently CA smog is (or at least was)  checking that the vehicle is using the oem and/or a ca smog approved tune, so I expect you'll fail inspection doing it.
    • davester
      Possible lifter tick after DOD delete

      By davester · Posted

      yes, leaking exhaust will mess up o2 sensor readings, which in turn messes up fuel trims.
    • Grumpy Bear
      Sugar Bears 2015 GMC Terrain SLE-2 2.4 AWD

      By Grumpy Bear · Posted

      286,740 Mile Services   8/6/2026   New AC Compressor. Refrigerant oil and dye, evacuate and charge system.  New exhaust system from cat back.  New Iridium plugs plus replace #3 coil Repair/rewire headlamp wiring (passenger side) and replace all forward bulbs. Polish lenses of both assemblies.  Pull rear rotors, clean and adjust parking assembly. Inspect, clean and grease front calipers. Check pads and shoes.  4 wheel power bleed of brake system. Dot 4 Reset idle speed 50 rpm higher New Serpentine belt.    Will need new pads in the rear in about 5K more miles.    Tax Title and License out the door just short of a grand.    AC clutch had bitten the dust. 1 year warranty on the pick and save replacement. Thing will make a Polar Bear cry Uncle.  He spent quite some time on the wiring. It was in the harness and he does nothing half. I got off cheap. I have considerable more light down the road. Sylvania Silver Star replacements.  Gas seal between the porcelain and shell of plug #3 was blown, cooked the coil. That was the cold miss.  Love the new exhaust. I can sneak into the neighborhood again.  Nice to have a working parking brake again. Belle Tire never got it done. That was disappointing.    This was one of her bigger bills and still way cheaper than a payment even given the oil consumption. This thing cost me under a hundred a month in repairs and normal routine costs. What is my incentive to replace it? 🤔           
    • AidenVorpagel
      cam upgrade in CA

      By AidenVorpagel · Posted

      hello I recently bought a 2012 gmc 1500 with a 5.3 and have a AFM disabler on it I'm interested in doing a cam but I'm worried if I remove the AFM system I will fail smog does anyone have info if they are able to detect that or a work around to it (not talking about hot smogging) please let me know thank you  

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...