The chart title says: "Corresponding tire load capacity"
It doesn't say front, rear, per axle, or whatever.
I need a plain English translation like - Curb weight + payload.
I think I can divide by four.
Aircraft weight ratings are simpler than pickup trucks'!
The chart is looking at the tires individually, without any regard to the rest of the truck.
Simple formula:
Go to scale, get weight on each axle. For each axle, take measured weight and divide by two. That’s the weight each tire on that axle needs to carry. The appropriate pressure can then be looked up in the chart.
If you instead want a number that’s safe for everything, you can substitute in the GAWR for the measured weight, as that’s what the axle itself is rated for. Remember that front GAWR is less than rear GAWR with these trucks.
So for example (pulling numbers out of my arse here), let’s say you go to a scale and get a front axle weight of 4000 pounds and rear axle weight of 6000 pounds. Your front tires should be at a pressure corresponding to 2000 pounds and your rear tires at a pressure corresponding to 3000 pounds.
Looking at the chart, that means front tires at…well it bottoms out the chart, so 35 psi. The rears at 50 psi (personally I would go for 55 psi to add a bit of buffer).
In the case of my truck, front GAWR is 4800 pounds, rear GAWR is 6950 pounds. Using those numbers instead of measured weights gets me pressures that will support what the axle is rated for, and therefore what I should never exceed anyways.
In that case the front tires each need to support 2400 pounds and the rears 3475 each. Based on the chart, that works out to 40 psi up front and 65 psi in the rear.
