Interesting shift on the thoughts about tire PSI. Many variables, and many opinions.
I'll keep an open mind about this, and reflect upon it a bit more, before shifting my current practice on tire PSI.
I currently do a four corner weight, while ready to travel. I take the highest weight per axle, and then look at the tire manufacturers PSI load chart. If the tire weight is within 25% of the ranges top weight. I move up to the next line. (Say the PSI on that line is 100, and the next level is 105, I go to 105 if the actual weight is with the upper 25% of the range.) I then add another 5 PSI to that. (105 + 5 = 110). This is what I run on that axles tire PSI. (Vs my placard reflects 120 PSI) (All of these PSI's, except the placard, are made up, just for this posting.) I feel that being within the bottom 75% of the tire range, and adding the safety margin of 5 PSI, provides me with an adequate cushion of safety. While lowering the PSI enhances the ride comfort, and I feel also lowers the potential damage of impact from a pot hole on a higher inflated PSI due to a bit more sidewall flex.
The placard is a worse case CYA PSI, IMO. And, I feel is dangerous, if an uninformed RV inflates to this value, regardless of the actual weight that they're carrying. Too many coaches were built over the years with axles that were close to, or actually over, axle weight capacity. As many items that are regulated in this country, letting people drive cars and trucks that have overweighted conditions. And or, under inflated tires PSI, puts all drivers at risk. A blowout, can cause loss of control, and that can cause an accident not only for the person driving an improperly maintain PSI level - but also for other drivers too.
I do agree with a line in the Toyo write up (many of them actually), that having tires set to the placard level, could provide a safety margin for those that do not properly maintain their tires PSI's - for a period of time...
One item that is different for me then stated in the Toyo write up, is the stated loss of PSI per month for a tire. Maybe it is unique to my tire, the Michelin XZE* (With the * meaning stiffer/thicker sidewalls.), but I can go up to 6 months without losing any noticeable PSI. Of course, other tires may have a higher loss of PSI over a shorter period of time.
>When in doubt, go to the placard PSI setting values.
>Do check and inspect your PSI, and tire condition, regularly.
>Do observe tire life usage, and plan on replacement based upon age.
As I said, I'll keep an open mind on this, and research more. But for now, I'll go with the load rating PSI, with the 5 PSI safety margin - and feel very safe doing so.
All, IMO. And it's important that everyone do what they feel comfortable with. Especially researching and making your own decision, based upon all the various sources of info available. Not just from a poster, such as myself, on a forum. Take responsibility to learn your rig, including tires, and then make your own decisions
Best to all, be safe, have fun,