I think my engineer friend would say "pressure, pressure and more pressure" to you. You say coach manufacturer says inflation should be 110 - 120 psi (?) and you are putting in only 95 and don't do anything unless your tpms says you are down to 92? What gives you the idea that the tire manufacturer knows more about your rig than the coach manufacturer does? And remember I also wrote this "Couple that with most MH's chassis are under shocked in the first place and you have a recipe for a problem.
All too often people want a soft and comfortable ride and when there are complications they then complain about it. They want someone to blame and most of the time they blame the tire manufacturer. I laugh every time I hear that the tire shop agrees with a customer that it is a defective Goodyear tire, what do you expect them to say? They don't want to make a customer mad and lose a sale.
Does anyone remember the Michelin XRV's and zipper blow outs? Did Michelin ever admit to a manufacturer's defect? I sure do not remember if they ever did. The consumer's claimed defect and Michelin, being Michelin(I am not a Michelin fan either), denied it and called it customer abuse. What was the abuse, most likely it was under inflation causing the sidewall to super heat and blow. Who caused the under inflation problem? The coach manufacturer? tire manufacturer? the consumer? I don't know, you choose. But, before you choose remember that the vast majority of users had NO problem with them. :S
Do tire manufacturer's ever make a defective tire? You bet they do, one of the worst was the Firestone 500 fiasco, what a nightmare that was.