Make sure you are using the correct pressure chart. Here is the latest: Michelin-Truck - Truck Tire Data Book New
Your tires pressure chart is on page 22.
I called Michelin about this just a few days ago and I was told to only use corner weights to determine the pressure to use. I was told axle weight alone is not accurate enough to use. I was told to use max tire pressure until I can get accurate corner weights. The problem with just using axle weights is in our RVs it's not uncommon for one side of the axle to be significantly higher than another. On my RV my fridge, bathroom, black tank, generator and slide are all on one side. Using the axle weight to determine pressure would be using way too low a pressure on one side resulting in a possible blow out.
I encourage you to call Michelin at 1-888-622-2306 and speak to them directly. They can explain it far better than I can. I was impressed when I called. They pick up first ring without having to jump through hoops. The person that picks up the phone is the person that will answer your question. Hands down the best customer support ever. After that phone call I was sure I will always buy Michelin tires.
My problem is there is no where around me that can do corner weights. So until I can get the proper corner weights I am using the upper end of the pressure charts.