My compelling reason was, as I stated but here in more detail, the coach's steering axle weight full of fuel and water was right at or slightly above the weight bearing capacity of the Michelin 295s at their maximum pressure of 120 psi. And the tires were showing stress cracks. Also, my replacement 315s are Dunlops, not Michelin. Five of the six rear tires are Toyos, one is Michelin. That's another story.
The coach has the wider rims so I get "full value" of the Dunlop 315s, that being a weight bearing capacity of 9,090 lbs (if I remember that correctly) at 130 psi. And the maximum pressure rating for the rims is 130 psi.
The morning cold pressures I use are 125 psi, 115 psi, and 110 psi going front to back on the three axles. Interestingly, within an hour the 315s on the front will rise to 140 to 145 psi according to my TPMS.