GaryA said:
If the mfg recommendation is 60 it must be for something other than a heavy motorhome.
Which means it would be lighter
weight. The tire manufacturer's tables are calculated for a specific amount of weight on the axle, not caring if it's a truck, RV or railroad car. It's not a one-size-fits-all figure, but rather a table with a specific range of weight vs pressure. Note on
this Michelin page that it is laid out by tire size (19.5" 22.5", etc.), by model of tire (XZE, XRV, etc.), and by single tire or dual tires, each table having pressure vs. weight. The tire obviously doesn't ""know" what's causing that weight (nor "care"), but physics cause it to react according to the various forces applied to it, which are strongly affected by weight and psi of pressure.
These tables are the tire manufacturer's way of saying, "This is how we've designed the tire to operate."
Note that these tables also show you the "Maximum load & pressure on sidewall" figure that is imprinted on that sidewall, the same as the highest weight rating for a SINGLE in the table, and so it shows that tires are NOT designed to have only a single pressure under all circumstances.