Normal use would be on a tractor/trailer. You can install a air pressure gauge to the rear axle air bag and come up with your own formula for what each psi increment is worth. Try stopping by a open trailer sales lot and see how we did it on a step deck open machinery trailer. The gauge will be installed in usually a metal waterproof box in front of the forward axle. Check it out this is really all you need. Hope this helps.
